I really like where you are going with this!
I know this is an informal poll, but herein lies the issue with generating a unified system. I just think it is so complicated, but well worth the effort to figure it out. Decisions regarding feats and ASIs as the pc progresses affects starting AS bonuses (however they are or are not determined) and vice versa.
So is there a hard ceiling on total AS points up to and including level 20? Now: after point buy, it seems every pc is guaranteed like 3 ASI from racial and from 0 to 10? ASI from class progression (a lot more for fighter, right?).
With more flexibility in the system as a whole, I feel like a good direction would be class features and feats being a single "thing" with more choices, more often as the pc progresses. This means a lot more work for this noble and much needed endeavor that I only discovered yesterday... reconciling feats, half feats (that give +1 ASI), class features (that progress in power and with hard prerequisite features prior to them), and +2 ASI class features (i get it that ive been working out and training everyday, and one day I wake up going from 16.99 str to 17.00 str... or I wake up one day finally being a master at that feat I've been practicing for weeks/months... but how do i go from 16.99 to 18 overnight?). It likely takes a prerequisite system (not simple, but crunchy and flexible, as the goal states), so that all of the four 5e "things" can be one thing.
So now, say there is 3x ASI for racial and 4x two-point ASIs for a typical 2-class level 20 pc, and about 8 class/subclass features along the way.... so how about a half-feat at every odd level (and no starting racial ASI). Maybe levels 2, 3, 4 are class core features (no half-feat at level 3). Nerf some of the very best feats, since they come with an ASI, and prerequisite them, so that GWM part 2 give the best and full benefit (and you gained 2 AS points alongside those 2 half feat).
Anyway, this ramble is not meant as a suggestion or solution. Its just to voice the interdependency of every small tweak upon the next 300 pages of core rules.