The following quote comes from nowgamer.com:
“I can answer that: no. We don’t have the time to fully recreate every single character who’s been in Smash Bros at this point,” Sakurai explained.
“Adding new characters is not a simple addition – it’s really multiplication. The amount of work, adding a character is multiplied and becomes bigger and bigger as you go. We can’t because of the amount of work it takes. However, I do believe I understand that each character has its own set of fans out there who really like that character.
“So we’re not going to cut characters out of the way, we’re going to put in as many characters as we can, we really want to do that, because it’s good for the fans and good for all of us. But in the event that we do have to cut some characters, I’d like to apologise in advance to those fans.”
Now, let me riddle you this. Would you rather have a new Smash Brothers game in the next year or wait another 2-3 years to give developers a chance to flesh out more characters?