Vicarious Visions is trying to assuage our fears, though, confirming to MTV Multiplayer that Wii version will have downloadable content. According to Karthik Bala, CEO of the company, the DLC will even be actual songs (as opposed to the user-created content that's also a feature in Guitar Hero World Tour).
Bala didn't elaborate on that last feature (called GH Tunes), so we're not sure if it will make an appearance on the Wii; the CEO says that more details on GH Tunes are still to come. We do feel better about the downloadable content though -- at least a little bit (old habits die hard).
Gallery: Guitar Hero World Tour