The problem is that there's just not that many females in the Nintendo universe who are as significant as Samus, Peach, and Zelda are. I say Nintendo should introduce some new game franchise with female leading role!
Basically this.
We cannot blame Smash for not including interesting female characters simply because companies don't
make interesting female characters. Smash can only work on what already exists, and what already exists is very lacking in female representation. You can say the same thing for non-white characters (Ice Climbers are def. ****** but other than that the characters are all to my knowledge white or some light-skinned but unnamed race).
I don't want female characters to be included for the sake of including female characters. I don't want female characters to be shoved in and end up playing poorly because then people go "oh, the female characters play poorly! Ugh!". I want female characters that are awesome and that everyone, male, female or otherwise, enjoys. For example, Zero Suit Samus made me play with Samus which I never did before, and it made me really appreciate having a woman character who kicks butt directly. Peach and Zelda have their appeal, but Samus is cool in that Michael Jackson
bad sort of way.
Unfortunately, being that female representatives of franchises are few and far in-between, I doubt we'll see any worthy female candidates. Lip is one of the few I support, but her chances are so small that I can't see it happening.