But with that same argument, she would be winning more tournaments and more players would've been crying about her during the Super and Vanilla days. But instead they were complaining about Ryu, Sagat, Rufus, etc.
Is she a good character, sure. But like Find said, it's a matter of matchups. America lacks a Viper army. Probably because of the cost of entry.
Remember when F.Champ put America on blast last year in that interview after SoCal Regionals? He basically said there wasn't any good Akumas.
It's the same for Viper.
And right now, Yun, Yang, Fei Long are the more b.s. characters.