Had this been any
Smash entry other than
U/3DS, I would've agreed with that; even
Brawl only had Peach, Samus, Zelda and Nana in a cast of
thirty-six other characters, some of which had ambiguous genders (like Jigglypuff), and Zelda had never been properly playable in a mainstream series title at the time. In
U/3DS though, this isn't an issue anymore because there was a pretty big influx of girls into the roster, so I don't think the "we need more women" argument holds water anymore... which might be why no one has pointed it out.
Fortunately for Shantae though, she has plenty of other, more worthwhile merits that could earn her a spot in
Smash. I wouldn't be supporting her if she didn't.