Hey, maybe Microsoft paid them a grip of cash to be exclusive for a little while. After all, you can't tell me that the Wii version of Rock Band takes longer to develop than the 360 version.
Except that Rock Band was never a 360 exclusive and was released on the PS3 at the same time as the 360. So are you suggesting MS paid a moneyhat specifically to block only the Wii release?
Guitar Hero: World Tour is getting my money almost entirely because I already have Guitar Hero 3 and might as well get extra instruments I KNOW will be compatible. My existing guitar controller can be the bass for World Tour. Guitar Hero got my initial purchase entirely because Rock Band screwed up. In reality the idea of a whole band is cooler to me and had they released a non-gimped Wii Rock Band around the same time as the other versions I would have bought it instead. Probably a lot of Wii owners are in the same boat as me.
On the flip side I imagine GH: World Tour will be incredibly successful on the Wii but only moderately so on the other consoles. Few people are going to want to own two complete sets of instruments. On the Wii all those Guitar Hero people like myself will be upgrading from one guitar to a full band for the first time. However that isn't the case on the other consoles since people did that already last year with Rock Band. Frankly I think the cost of keeping up with these games is too high for most people and it's very naive of both companies to think they can continue to release these expensive bundles and have them constantly sell.
Guitar Hero 1 was the first one.
Guitar Hero 2 was the first one on the Xbox 360.
Guitar Hero 3 was the first one on the PS3 and Wii.
Rock Band was the first one to have the extra instruments.
So everyone has had a chance to get all the appropriate controllers regardless of what console they own, with the exception of Wii owners who specifically choose not to buy Rock Band. But after this what's the point? When Rock Band came out I saw the Special Edition everywhere in big piles. Well if they're smart they better hold back on the Rock Band 2 Special Edition because there is no real reason for most people to buy that. Newcombers are the only ones that need it, everyone else will probably just get the standalone disc version. They better be smart enough to realize that the demand for the hardware is not so high anymore.