Back in the golden age of BioWare, their party members set a new standard for what a party member could be in an RPG, especially a western RPG with a (more or less) customizable protagonist. Which is why it’s so infuriating that the party limit for these games is as low as three.
I’m defining the “golden age of BioWare” here as the time between Knights of the Old Republic and Mass Effect 2, inclusive. You can fuss with the exact boundaries of that, and I’ll freely admit that the only reason I’m not including Neverwinter Nights is because I never played it. A quick Google confirms it has a maximum party size of two, and if it’s got the character quality of Baldur’s Gate before or KotOR after, that isn’t nearly enough. But let’s stick to what I have direct experience with.
In Knights of the Old Republic, there are a total of ten party members (including the player character), a maximum of three of which can be in the party at any given time. This means certain party members are immediately put on the bench and never leave. Exactly who that is varies from player to player, but T3-M4 is basically never in anyone’s party for longer than the one mission in the Sith base immediately after you acquire him. I forget if it’s possible to turn around and ditch him immediately after he gets the main door open, but I’ll bet most repeat players do that if you can (I feel obliged to give him at least one mission to justify the story beat of recruiting him).
Carth Onasi is pretty bland, a Han Solo knock-off by people who don’t really get Han Solo. I use him sporadically on Taris and Dantooine, and then never again once HK-47 gives me a second heavy combatant to go with Canderous Ordo for combat purposes. His concept art makes him look a lot more like a dad in his late 30s or 40s than his mid-20s looking in-game model, which I think would’ve redeemed him a bit, since “embittered veteran who thought he was done after the first war” fits his backstory much better. Admittedly, at that point he’s pretty poor for the game’s only male romance option, but KotOR’s romances were terrible anyway.
Speaking of which, Bastila is barely more interesting than Carth, but mainly because you can tell she’s constantly closer to losing it than she’s trying to let on. Her actual fall to the Dark Side is still bizarre and stupid, though. Losing faith in the galaxy after a traumatic experience makes sense, but why would you then swear allegiance to the person who traumatized you? Particularly for an experience that lasted, like, two days, that doesn’t make sense. I use Bastila for early Force heals but ditch her as soon as Juhani is available.
I sometimes have Mission and Zaalbaar follow me around Taris for a bit just because they’re supposed to be a team, but I bench Z pretty quick and I expect most people do so even faster than I do. The one time he’s potentially relevant on Kashyyyk, he’s forcibly benched for 80% of the episode. Mission herself fares better, since as far as skill monkeys go it’s her or T3-M4 and there’s no competition there regarding who’s more fun to keep around.
Canderous Ordo and HK-47 are the only Dark Side characters in the game, so they have the niche of being two evil bastards you can bring with you for your evil bastard playthrough. Even then, you’ll likely swap one of them out (statistically, probably Canderous) for Jolee Bindo, because he’s neutral and he can Force heal and that is the most powerful ability in the game.
Which brings us to the party that most people arrive at: One of Jolee Bindo or Juhani, and then either HK-47 or Mission Vao depending on how much you need a skill monkey. Even for the people who prefer Canderous or Carth as their heavy, or who like to stack up Jedi and take both Jolee and Juhani, or who take care of Force healing personally so they can have both HK and Mission, or whatever, there’s a set of two characters you bring with you almost anywhere, and maybe you occasionally bring someone who seems plot-relevant, but even that’s a big ask when you have exactly two slots open. If someone really likes HK-47, that leaves them with exactly one spare slot to cover both optimization and plot relevance. If they really like HK-47 and Jolee Bindo, they might never use anyone but them.
On the other hand, if KotOR supported six simultaneous party members, that fifth or sixth party slot would be much less valuable and much more likely to get used. This would be extremely overpowered for the existing content, so obviously there would need to be more enemies, and many of the combat areas would have to be about bigger to accommodate having 15-ish people fighting in them instead of 8-ish. Also, the combat system would have to be overhauled so that more party members can be left to their own devices more often. KotOR’s environments and combat are both acceptable but not amazing, though, so it’s not like these overhauls risk destroying something vital to the game. With six party members, it’d be much easier to always bring Zaalbaar when I have Mission in the party, or to have T3-M4 be a constant tag-along like R2-D2. I could keep Carth around for pretty much all of Taris, and periodically bring him along in a sixth slot, rather than swapping him out for Canderous (and later swapping him out for HK-47 in turn) and then never using him again.
Other games are similar. Jade Empire has only one companion at a time, even though it takes more than half the game to even get seven party members (including the player character) such that a party of six would have to pick one to leave behind. Such a large party would certainly have dashed the game’s ambitions of being a more action-focused RPG (if you have five people helping out, either your party members are useless or your personal contributions get lost in the noise, so some kind of party command is required), but those ambitions were firmly dashed anyway, so who cares? I can imagine an action RPG where the combat is good enough that adding more party members would be a bad idea, but that RPG isn’t Jade Empire. Even for that game, if you’re going to have so many different party members, I’d want an excuse to use more of them (like if many quests require you to split up into many teams of two – lower difficulties could give the option to skip all routes except the player character’s, or could just make the combat sufficiently easy that you can button mash through no matter how unfamiliar you are with your character’s moveset).
Jade Empire’s one party slot at least gives an obvious way to give each party member spotlight: Use whichever party member you most recently recruited until you find a new one. But that means your childhood friend Dawn Star gets benched early on in the adventure and you never see her again.
Dragon Age makes me wonder if BioWare saw the problem, but really just couldn’t break enough away from their D&D roots to really address it? While Dragon Age has its own RPG system not calling back to any specific tabletop ruleset (as opposed to Baldur’s Gate and KotOR), it’s still clearly derived from D&D combat, which makes it almost unmanageable if the party gets too big unless you’re able to pause (or just take turns). The slightly raised party limit of 4 is pushing up against what this paradigm can handle, but also there’s twelve party members (thirteen with DLC), which means you leave two-thirds of your team to make sure no one takes your seat at the tavern.
The first Mass Effect at least gives you a small total number of squadmates to pick from, but you still have to leave over half your party behind (two-thirds if we don’t count Shepherd as a party member), and it’s particularly aggravating to have to do so in a relatively grounded sci-fi world where “almost but not quite a full squad of nine” is a perfectly sensible number of people to be bringing with you to an away mission. Mass Effect’s combat was beginning to approach something worth saving, but it never really got there even in Mass Effect 2, and certainly it wouldn’t have totally collapsed if environments were a bit bigger, enemies more common, and you had a second fireteam of three that you commanded as a single unit in addition to the two squadmates in your own fireteam you command directly. Leaving one person behind to secure the ship is less objectionable than more than half your team, even if it does mean that one of Kaidan or Ashley will get benched and stay there for the entire game (this will make the “who will die” choice near the end even less impactful than it already was, but that already suffers from asking you to choose between the two characters you care the least about so there isn’t much to lose there).
Mass Effect 2 is really bad with the party being massively larger than the squad size, but does introduce two new features to fix it: Companion quests that focus on a specific party member during which you’re bringing that party member (in addition to a favorite character who permanently occupies the third slot), and the suicide mission at the end which requires you to use all of your party members. The companion quests in particular are a good idea. You can see seeds of them in earlier games with side quests that are directly to do with one of your companions, but often less than half your companions would have them and you usually weren’t even required to bring the relevant companion for the quest. The sand people are way too powerful for me to bring Mission to their camp, so she’s never come with me to rescue her own brother.
By the time you get to the eleven (thirteen with DLC) party members of Mass Effect 2, just increasing the party size isn’t really a viable solution anymore (I could imagine a game that drastically overhauls the mechanics such that it focuses on platoon-level combat but with each individual soldier being their own character, and that sounds awesome, but it’s a completely different game from Mass Effect 2), so these were good ideas. The squad still could’ve easily stood to be twice as large as it was, though. Leaving half your team to guard the ship still seems kind of excessive (the Normandy seems to have at least twenty non-party crew who, even if they’re individually much less badass than party members, are presumably all military trained and likely have overwhelmingly more combat power between them than Shepherd’s canonical three-person away teams), since surely you would want to concentrate power in the people who are going directly towards danger rather than the ones guarding the escape, but you’d still want some people guarding the escape, and at some point the party gets big enough that you’ve shifted genres from RPG to some kind of tactics game. In any case, from a gameplay perspective having six party slots (or really five, since the first must always be Shepherd) makes it much easier to swap the characters in the fifth and sixth slots around so that you don’t end up with one core team you bring to everything and everyone else is ignored as much as possible.
Ultimately, if you’re going to have this many party members in a game, it should be possible to bring at least most of them into combat with you.