Sega just has a problem with pumping the series full of characters regardless of wether or not they are needed or fit well for the story, just look at colors on DS and how many people they shoved in.
I DEMAND A BLAZE SPINOFF!
I'm tired of looking at the modern cast that we have and have had since SA2, I want to see Mighty and Fang return because they can make the game feel more fresh so we don't have to look at the same dull characters all the time.
I would like to also see the chaotix play a bigger role in a story.
I would say that bringing back older unused and forgotten characters is much better than introducing countless new ones.
I think we'll start to see that change, given that SEGA wants to start focusing on merchandising again. That usually means, lets establish more characters so we can make more toys/etc.