As much as I want bandana dee, he really isn't an important character. Smash bros is for Nintendo's biggest stars to battle out in one great game, and I don't see bandana see as a big Nintendo star. He's one of those less important characters like Birdo, Waluigi, Tetra, dark Samus, Poo (earthbound), and tom nook, etcetera. These characters seem to have importance, but only a little, and to their own series. I do not believe bandana is important enough, like the other characters I mentioned, to be in ssb4.
Source:
http://ift.tt/1kP5HOC