I am also going to buy a Wii U just to play Bayonetta 2. I mean, Bayonetta was the top game on my Best of 2010, so why wouldn't I? Nintendo made a smart move by picking it up. It reaches a core niche market that they've been missing for a while. As long as they give Platinum free reign over it, then there's no reason for me to NOT buy a Wii U for that game alone.
It's just like with PS3. I've always said that I would buy a PS3 ONLY if Dark Cloud 3 ever came out. It's the sole thing that would make me buy it.