Azzy
ᚳᚣᚾᛖᚹᚢᛚᚠ (He/Him)
That's a bit of circular logic. Something having been presented as X isn't a good argument that it should always be presented as x in the future (especially if it can also still be presented as x).They should exist, because the racial abilities support their existence. Elves ARE more dexterous than the baseline in D&D. This is fact. Halflings ARE more dexterous than the baseline in D&D. Half-orcs ARE stronger than the baseline in D&D. These are also facts. Those facts mean that the stat bonuses to reflect them should exist. Nothing in D&D is immutable, but not being immutable is not good cause to change them.
The average elf being more dextrous than the baseline can be shown in their ability score arrays in the Monster Manual. However, there's no reason for PCs to be beholden to the average. Moreover, it's unnecessarily constraining new settings or homebrew settings with the standard archetypes instead of letting them explore Elves That Are Different without needing to create yet another elf race/subrace. Having floating ASI (or none at all) and cultural features being swappable allow for exploring different archetypes than those presented in Greyhawk and the Forgotten Realms. You'll still be able to have your traditional elves (and such), but others will be able choose a different direction for their characters or settings if they so desire.