Well as people pointed out already Dragon Quest usually means a system will get better RPG support. Not all of it, of course, but quite a lot probably. What I'm really keen to know is whether they are going to do with Dragon Quest X what they did with Dragon Quest IX: Rocket Slime, Monsters: Joker, Dragon Quest IV, V, VI and now IX on DS... each game was bigger than the one released before it. Now if they do the same with the Wii (and they could as they want to milk everything out of the franchise) they could very well release more games of the series on Wii. They did the same on the PSX and the PS2 if I remember correctly.
Edit: What I mean is that it seems to be a common procedure for Square Enix to remake older titles or release spin-offs for the console they develop the next Dragon Quest for. So we could very well see Dragon Quest VII and VIII remakes and things like "Dragon Quest Monsters: Myamoto" or "Dragon Quest: Ultra Slime" or I dunno what.
I call it milking a franchise to death but I'm sure people would buy those things anyways.
