I didn't understand the whole point of the scratch-and-sniff cards that came with EarthBound, but if they moved the sequel to the DS, then they could at least have some in-game scratching!
The DS needs more RPGs, if only because touch-screen menus would be so handy. More room, then, for wacky psychedelic, trippy, drug-induced/inspired background visuals during battle!
There are still multiple more GBA owners than DS owners, so I guess they'll feel more comfortable continuing a not-that-well-known franchise where it'll probably sell better. If only they could find a way to make it a killer app for the DS (though you'd think with Nintendogs, Mario Kart DS, and AC:WW than any Nintendo gamer would surely get one by this holiday season if not already).