Probably because the size of the full-resolution "skins" are of significant size, which may be an issue on phones with limited storage - especially if they impl

Probably because the size of the full-resolution "skins" are of significant size, which may be an issue on phones with limited storage - especially if they implement custom assets to fit each size rather than just scaling. Which also may happen to be correlated to the sort of phones who won't use the highest quality versions in the first place.