Uh dude...
They have
plenty of space. And they overwrite the old sprites anyway :/.
Personally I wish they would update the Hoenn sprites, since they just look out of place. The D/P sprites sucked, and the style of them are way too different from the style of the HG/SS sprites. Also they should have updated Yanmega, Tangrowth, Lickilicky, Mamoswine, and Ambipom's sprites.
Also did anyone notice that they changed the color palette but not the sprites of a few Sinnoh Pokemon (and Registeel)? I mean, look at
Glameow's HG/SS sprites. Wonder why they even bothered changing the color palettes of some Pokemon you'll hardly see in-game.
EDIT: Oh, and about Whitney's age, I say f**k the anime. Just because she's 6 years old in the anime (okay, maybe older than that), doesn't mean that's her actual age in the games. IMO, I say all Gym Leaders are at least 18 years old.