I think if she's not JUST a set of tits, then it's slightly better.
This is from a girl's point of view, so maybe I'm not qualified to comment, but I always thought sexuality targeted at men was sexist in the sense that it's debasing males to a very basic element of their personality and they assume that ALL guys will ONLY play games if the girl is highly sexualised.
I don't deny that that there are guys out there who WILL play just for the boobs (I'm looking at the main target audience of Bayonetta and the like, here, even though she was a fantastic protagonist) but girls are JUST as sexual as guys (studies have found females respond to sexual images just as quickly as men - don't ask for a link, I was linked through a cracked.com article and don't remember which one - they don't market guys with their penises (peni?) out to women, even though women are sexual creatures too. Reeks of double standards. Not that anyone would want to see a naked dude in games (although don't get me wrong, it DOES happen, and it still strikes me as being wrong)...
But yeah, OP, I can see why you'd find it offensive! It's a very simplistic marketing ploy and degrades men in terms of males being seen as ONLY interested in the boob age.