Completely speculation, but my guess is that it is a $$$$ thing, plain and simple.
When you have Tate, Ripper, and Blaze, all three of those guys want to get a decent chunk of change. And arguably, Ripper is the best out of all three of them, and is used to getting paid at a certain level.
I checked out a few clips -- it was cool to see the three of them, but (total speculation here) if Ripper wasn't getting paid what he was used to getting, then I don't blame him for stepping aside.