Because they want to play, say, a human fighter and not feel like their racial bonus is a waste
Then either pick a different race with a racial more suited to the class, or deal with the overlapping proficiencies. Submitting a suggestion to remove or rework an objectively good racial attribute because it doesn't fit a particular build is inane.
The whole point of Tasha's replacing racial ASI's with "do whatever you want - +2 & +1" (and Larian choosing to use it in BG3) was to stop encouraging or discouraging specific race & class matchups.
Any racial that provides such encouragement/discouragement is therefor objectively bad.
In a game / setting that want's races to be narratively distinct in a way that has strong mechanical results, that wouldn't be the case.
For an example, I'd never complain that dwarves in Dragon Age can't be mages.
I'd be fine with a game/setting that just straight up said "this race is stupider than others, and as such are inherently worse at being wizards" and gave them a racial that had a minus to Int with a boost to something martial
But that's just not the intention with 5e, and therefor BG3. Especially as of Tasha's, all race-class combinations are supposed to be equalized, at least for player characters.
Which means all versions of "then pick a different race/class for a better matchup" are frankly not fully valid arguments.
