Never really understood this viewpoint, because it's pretty much the opposite of how the matter appears to me.
Yes, it enables your hardcore char-op people to pick their package of racial traits while also getting their ASI of choice, but there are always going to be people looking to leverage their system mastery to gain as much player power as the rules allow, so lowering that ceiling doesn't change the fact that they will always aim to be at that ceiling. By contrast, people who don't have that level of system mastery still feel the selection pressure to align their racial ASIs with their class's primary ability scores - if you don't understand the system math well enough to be able to accurately judge how "necessary" that +2 is in the long run, all you're left with is the general knowledge that "higher numbers are better" and mountain upon mountain of online character creation guides telling you that any race without a +2 in what your class is good at is dead in the water.
You may not be "forced" to play a race with ASIs that align with your class, but there is a strong incentive to do so. Sure, you can play that orc wizard, but no matter what you do, it will take four extra levels (or eight, if using the pre-errata orc with the -2 INT penalty) before you're "as good" as you'd have been if you were playing an elf instead, and those class level ASIs you have to sink into INT to catch up could have gone into something else, like shoring up your CON score or taking a feat.
Floating racial ASIs eliminate that incentive and put every race on a level playing field, ability score wise. It's no longer mandatory that your orc wizard be dumber at level one than another player's elf wizard. You still have the option of playing with a non-optimal ability score array if you so choose, but people who just had a cool idea for an unorthodox race/class combo are no longer punished by default for picking it, and I think that the benefits for newer and less experienced players far outweigh the cost of letting optimizers eek out a bit more player power in a system for which, as you yourself note, it doesn't really make THAT much of a difference.