why would they release it for the PS2 instead of the PS3?
Probably because they don't want to do extra work for the graphics. If they simply developed it for the Wii and then ported it over to the PS3/360 without changing the graphics, "professional" reviewers as well as the general gaming populace would complain for ages that it looks exactly the same. Let's face it, graphics are huge for a lot of people, and nobody wants to play a PS3/360 game that looks like it could've easily been on the PS2.
As for me - I can't see myself buying this game. Not because I think it's going to suck, it's just that I won't be buying games for quite a long time and when I finally do
start playing games again I'll likely play the ones in my backlog as well as go through some of my RPGs again.
Then again, my friend has a Wii. So maybe I'll buy it for the Wii and just leave it at his house, and when I go over on the weekends I'll play it.