They just don't know what to do with the franchise, Sonic Team and affiliated studios have been experimenting with the newest, coolest, hippest, raddest way to reinvent the wheel, and they never broaden or improve any of their few successful attempts.
Nobody wants Sonic Boom. Nobody REALLY wants Sonic Adventure 3. Nobody wants an Angry Fucking Birds crossover, nobody wants to play Virtual Olympics. I want a couple tried-and-true gameplay formulas back. Stuff that everyone knows works. I am not talking about the Adventure formula. Unleashed/Generations/Colors gameplay worked well, but was never refined to a point in which it could be considered a perfect game. There was always something wrong, and with every iteration, every improvement, there was a new problem. It's like the Hydra of game design.
Remember SEGA, something can only be stale if you let it, and honestly, I'd rather people complain about the games being samey, but good, rather than god damned unplayable.
Give it five years. Five short years to actually toss around ideas, make a gameplay engine, put some fucking effort, some soul into the game you're going to put out. Everyone and their mother knows that Sonic Boom exists to ride on the coattails of Skylanders. It's an aesthetic imitation of western, 'Dreamworks-y' productions. You're not fooling anyone here. Do something right for christ's sake. You know this shit is getting pretty bad when the fanbase of the original work can put out a gameplay engine that's more competent than the real McCoy.