I can't speak for everyone, but I like Medusa for many reasons other than her sex! For starters, she's the main villain from Kid Icarus (and one of the major antagonists from Kid Icarus: Uprising), which automatically gives her prominence in the series and, consequently, makes her a great pick to be playable. But beyond that, when you start to think of what she could do, she sounds like a unique and fun character! The classic Medusa stoneforming abilities and her Underworld Army underlings alone could largely fill out her special moves, then add in the myriad of lasers and projectiles and such she used in Uprising and you've got a pretty good pool of abilities to draw from for a Smash moveset. Of course, that great redesign that she got also makes her that much more of an appealing choice. I was always way more interested in seeing Medusa become playable than Palutena, and I still maintain that if there's ever a third unique Kid Icarus character it should undoubtedly be Medusa. The fact that she is a female villain specifically is only one more reason why it would be cool to see her.