I think AFO was alright as he was originally presented. In a setting where social value is determined on the internship one gets through innate superpowers, his ability to have all the powers through the means stealing another's validity as a functioning member of society is rather frightening and setting appropriate.
The problem is Shigaraki was set up to inherit an element of this struggle, that element being which subverts the structure of the Hero-based society. As much as All For One vs One for All continues, it's paralleled in Deku creating something out of nothing and Tomura wanting to make nothing out of everything.
Of course, of late Tomura's inheritance of AFO's mantlehas been made quite literal and I think that's where it feels kind of cheap.