RPGs aren't exactly the easiest genre to make, but at the frequency at which they appear at PS2 and DS, I don't think that's the issue with the Wii. They do take some lead-in time though. I think that we'll be seeing more of them as time goes by, already we have Symphonia 2 coming, Crystal Bearers looks really nice, and there's the new Rune Factory and and that RPG that just got announced this week. There's probably some other stuff that I'm missing, but once the RPGs come and sell decently I think that the Wii will follow the DS with lots of 'em. Hell, the first few DS years was hurtin for an RPG too, I remember having to play games like Deep Labyrinth and Tao's adventure to get my fix, but now we're swimming in them. Wasn't FF3 the first real "big" RPG for the system?
The Fire Emblem Wii game is really good, a shame that most people didn't take notice of it. The Chocobo Dungeon is also better than one might expect, and I liked Baroque.