D&D’s 3rd edition had, as part of their development process, a mission to find out what things were so core to D&D that the audience would revolt if they were changed, and which they could overhaul as completely as they pleased. For example, there had to be some use for all the funny shaped dice, because D&D players like their funny shaped dice, so you can’t switch everything over to standard six-siders even though that makes it easier for new players to get started. It was determined that numerical bonuses on magic weapons and armor were too beloved by too much of the playerbase to be dispensed with, so instead the game’s power curve was built to accommodate +2 longswords and such.
And they decided that they could not change the six D&D stats: Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma. This is too bad, because those stats are bad. They do a poor job of describing characters and a poor job of defining what parts of a character are expected to be under the player’s control and which are expected to be abstracted away by dice.
The need for some kind of perception-based roll is obvious. The GM can’t very well just declare that the monsters have surprised the party because they prepared an ambush – clearly, there is some chance the party might spot the ambush using their eyes and ears in a way the players at their tables cannot do, on account of the thing to be spotted being imaginary. Equally clearly, certain character archetypes, like the elf or the ranger, are much better at noticing these ambushes than, say, the fighter or the wizard. So your stats definitely need to cover spotting things like clues and ambushes, and definitely need to vary from one character to another.
But why is the associated stat Wisdom? You wouldn’t necessarily expect a perceptive thief sort to necessarily be extremely wise (though you wouldn’t expect them to be extremely foolish, either), but you would expect them to be very good at spotting ambushes and traps. Why is Survival associated with Wisdom? While that specific skill is from the 5e skill list, earlier editions also associated similar skills with the Wisdom stat, despite the fact that “impulsive barbarian who is nevertheless very good at hunting deer” is an obvious archetype (I have a fanboy compulsion to point out that this does not describe Conan the Barbarian as originally written by Robert E Howard, but it’s been a long time since Conan was the only or even primary inspiration for the Barbarian class and archetype). You can hack your way into it by giving the barbarian proficiency/skill points/whatever your specific edition uses to make skills improve with level, but a Cleric trained in Survival (or equivalent) will always be better. Characters with strong willpower are automatically better at working with animals, despite “easily startled animal lover” being a pretty straightforward Druid concept. You would expect someone’s Wisdom score to either increase or plateau with age (old fools exist aplenty, but they were fools when they were young, too), and yet eyesight and hearing get worse the older you get, starting almost immediately – few people can hear the “teen buzz” by the age of twenty, which is why it’s called that.
The division between stats is inconsistent. STR and CON are split apart, which leaves the conceptual space for the two stretched so thin that CON has no skills associated with it at all, and STR only gets one. CON gives HP and is a common save against nasty effects, but STR only contributes to attack and damage – DEX does that, and it has three skills (plus Thieves’ Tools, the rogue skill which has cunningly disguised itself as a tool proficiency) associated with it, and it’s associated with a common save, and it increases your AC in most armor. And there’s an obvious point of division between full-body agility and manual dexterity. Sleight of Hand, Thieves’ Tools, and ranged/finesse attack and damage would be covered by Dexterity, while Agility would cover the AC bonus, Acrobatics and Stealth proficiency, and get the saves against area attacks. Alternatively, combine STR and CON together to bring it up to par with DEX, which is probably better balanced with the other abilities (although as we’ve already discussed, WIS is a dog’s breakfast of concepts already).
Plus, while the mechanical function of Intelligence is fine, both it and Wisdom are named after things which should be coming from the player, not the character. A lot of Wisdom’s problems as a stat come from trying to tie together several unrelated mechanical functions, but also the basic concept of being too wise to fall for a trick is something the player can and should be doing themselves. Likewise, being smart enough to out-maneuver an enemy in a fight or politically or whatever should be based on player decisions. These kinds of decisions are the core of the player’s input into the game, strip them away and what game do you even have left? Roll an INT check to see if flanking that enemy is a good idea? Roll a WIS check to know if the princess is trustworthy (Insight already gets close to this)? At some point you’ve automated every choice a player can make and are playing a particularly cumbersome idle game.
The things covered by the INT stat – a collection of skills, casting for the Wizard and some wizard-flavored sub-classes, and a very rare save – would be much better represented by an Education stat. WIS needs to be redesigned entirely, either renamed to something like Perception (the skill would be cut and its functions turned over to Perception saves) or else cut entirely and its functions split up between other stats. Either STR and CON need to be combined, or else DEX and AGI need to be split (depending upon the balance considerations, which vary depending on exactly what edition you’re talking about – DEX is much stronger in 5e than in 3e, for example).
And also we need to move away from stats going from 1 to 20 with 10 being the average which gives you +0 and instead have a system that goes from 1 to 10 with 5 being the average which gives you +5, and then increase all DCs by 5 to compensate. This is the kind of thing that would break backwards compatibility so it’s a very bad idea at this exact moment, but whenever we’re breaking backwards compatibility anyway, please cast off this final remnant of the jank era of the 70s and 80s when people were still figuring out how roleplaying games worked and the resulting systems were overly complex and showed the scars of being on their twelfth revision when the creator finally said “fuck it” and pushed it out the door, ready or not.