Haha.
If they wanted it to look like a woman so badly, they should've just made it a woman! Attention: Sephiroth needs a personality - STAT!
In terms of "badass"... I don't think Square goes for this image very much at all. We mostly see: Vile, elegant, ruthless, villanous, insane, devious schemer, but yet I can't think of one that had "badass" as the primary image focus. I certainly don't think Sephiroth looks very badass to be honest. Aside from the woman-hair aspect, Sephiroth seems to be the one least-accomplished FF villains in the series. Most of them manage to wreak heavy destruction of some sort before they're finally defeated, but Sephiroth did very little. He almost had something going with Meteor, but it was countered. I don't think torching a small town or killing Aerith really count as "heavy destruction" either.
They are! Evil corporations are generally shockingly ruthless. For some reason, I've always liked the "evil offices" concept in a lot of video games/anime/movies/etc.