While it's not the only reason, one of the primary motivations beyond removing racial ability bonuses in 5e (and D&D One) is so every race can be optimal at every class. Whether optimized race/class combos are a thing one feels like is necessary, it seems to me the unasked question here is my are classes still tied to specific abilities to begin with? Why can't you have a dexterity based fighter or even an intelligence based one? They'd be a bit different "in the fiction" from a strength-based fighter, but wouldn't that be part of the fun?
I know primary ability scores are still a thing for legacy reasons, but if you can given up racial ability bonuses (and penalties!) and broaden spellcasters to be able to use various ability scores for spellcasting, then I hardly think this is a bridge too far.