One of the big issues with releasing so many versions of GH is that those tracks could easily be added as track packs or DD purchases rather than full release games.
This is likely one of the reasons why more people are beginning to prefer the RB franchise, which has allowed players to transfer tracks allowing for one large library without having to switch games.
Of course the Rock Band Beatles edition shows EA is hardly above doing the same thing, although in all fairness, the art direction is very specifically Sgt. Pepper/Beatles-like in addition to the Beatles specific game controllers. A track pack wouldn't do for a proper release.
But special band editions, while catering to a very specific audience, are still profitable, even if they don't sell the same numbers as the "main" editions.
But the reason for all the retail releases is the simple fact that they continue to sell and so Activision will continue to play the cash cow until it stops.
Either you like music rhythm games or you don't. If you do, you can only play X track on expert near 100% so many times before you want more tracks (or better yet, just learn how to play a real instrument already).
The biggest complaint I hear about any music game is that "it doesn't have enough tracks that I like" or "I don't know any of these songs."
It takes a huge amount of releases to change that, assuming consumer interest in the genre continues to hold.







