I'm not against re-separating feats from ASI marks, however it's not as simple as some folks initially assume; in the current 5e structure, ASIs aren't tied to character level, but to class level, and some classes get more than others; disentangling feats from ASI levels creates a difficult to resolve mess as a result, when multi-classing is considered [...]
Feats are meant to be strong and interesting, and they're meant to be a viable substitution for a full ASI. In the early design days, this was done with a strong thought towards the new bounded accuracy philosophy that was being put into the core of the system; branching out and doing interesting or different things was intended to be made more appealing and more valuable by virtue of the the fact that your core ability score bounding was not as swingy as in previous editions. They were intended, at least in terms of the combat-centric ones, to add versatility more than they added direct power, because that versatility was, in itself, powerful in the new system. [...]
None of this is intended to really argue for or against anything or anyone, it's just some food for thought to add to the discussion.
All true, which is why it'd require an overhaul of the feat system instead of just giving every character both a feats and an ASIs at every current ASI level (or alternating).
Imo ASI/feats are tied to class level largely because of fighters; since the default fighter is a fairly empty class they need those ASIs - in particular feats - to have identity, power, and versatility. This would be partially fixed if ASIs were tied to character level but feats tied to class level. Mutliclassed characters would then get ASIs at the same time they get other class features, but that's fine (adding 2 stat points is a simple endeavor). And feats could remain tied to class levels, so that fighters & rogues get them at their dedicated feat-emphasized levels.
Feats would almost certainly have to be reworked. Aside from the fact that the current feats vary wildly in power (GWM/Mobile/War Caster/Observant/Lucky vs Athlete/Linguist/Weapon Master/Second Chance), I agree with @Tuco that these separated-from-ASIs feats should be revamped to not include ASIs. Balance-wise, feats could be equivalent to one ability point: a simple fix could be to remove the "+1 ASI" from all the feats that have that and then split the bigger feats in 2. E.g., Polearm Master would turn into one feat giving the BA attack and another giving the opportunity attack.
