That's right everybody. This game will singlehandedly destroy the Lego company. I have no idea what we will do. My hobby's going to go out the window.
Do you guys really think this game will have such a crippling effect on the company as a whole? How many crappy games did TLC make in the late 90's early 00's? A lot more. Did TLC roll over and die after the first one failed? No. As far as I'm concerned, the only GOOD lego games ever released are the original Lego Island, and the recent string of licensed games. From what I can tell, Lego Universe looks fun, but there's no way to know until then. In general, Lego is not successful at making games, but they do have a few flukes here and there that are actually good. That's part of the reason why people were shocked when the first LSW came out at how enjoyable it was. So even if this game is a flop, it will not cripple the company.
It's perfectly alright not to be interested (I myself think the idea is interesting, but I don't have the time for another rock band game, since I'm waiting on the Beatles one to come out in September), as the rhythm game genre is starting to get tired, and the idea might seem so out of left field, but it is not damaging. It seems to me that parents love the idea of more child friendly games like these, so there is a market. It won't sell phenomenally, but it probably won't sell enough to encourage another one.
And to support another point, I also agree that music sets in general do have some demand as well. How many of the rookie stop motion lego music videos on youtube would be itching to use real molded pieces of instruments?
And this sort of idea doesn't just happen. The licensed games happened because Lego owned the licenses. Lego made a Drome game because Drome was part of Racers. Same with Rock Raiders. And Bionicle (repeatedly). And Alpha Team. And the mini Racers game, and the castle game. This idea is so unrelated to what they usually do, that it must have been triggered by a significant demand to go out on a limb. Therefore, somewhere out there, whether you think so or not, there's a demand for this game.
EDIT: One thing I really wish for this game would be for them to implement an song transfer tool like the one available to RB2. If you could transfer songs from the other Rock Band games, that would make this game appeal to a much wider audience, all the while not compromising the family friendliness of the original setlist. Younger kids can play the songs with it, and older folks can transfer DLC, RB1, RB2, or song packs to LRB for a more exciting set. Something like THAT would convince me to buy the game.