Why is that? If I am allowed to ask.
I know this is going to sound stupid and petty, but I did not enjoy Kid Icarus: Uprising at all (the gameplay, the controls because I'm a leftie, and the attempts at comedy). I admit to leaning towards villains in an argument about 65% of the time, and Palutena's character from that game was somebody I could not tolerate because she came off as lazy and annoying. Medusa, on the other hand, I sided with and wished that she had a much bigger impact in the story than what she actually did (and, hopefully, make a Smash Bros. appearance once of these installments, but that's a pipe dream). Maybe it's because I am a bit of a grump in real-life.
I can tolerate fanservice from a character that I can respect, and if I wasn't a fan of Palutena, I wasn't going to enjoy some of the stuff she's allowed to do.
Fiora, on the other hand, not only do I tolerate, but I absolutely respect, considering the adversaty she went through, and when you finally get her back, she is ready to fight the world.
And, given what she now has in possession, can beat the world, too.