Zig, I think the interesting question that we should be asking is: Is appreciating women's (or men's) figures inherently sexist? I don't think that it is.
If I look at a woman and think that she has an amazing figure, then I go on to ignore everything she says because I believe that she's so pretty that she couldn't possibly have anything useful to contribute to anything, obviously that's sexist. I personally have seen many women that are drop-dead gorgeous and very much in charge, entirely capable of making better decisions and doing more good than many of the men around them. I still wouldn't mind seeing them in a bikini. Is that sexist, or is that just me behaving as nature intended?
It's natural that hormones will to a certain extent dictate how a man looks at a woman (or even another man, in some cases). Trying to put a negative label on that is absurd. Sexism begins when we start judging someone's mental capabilities based on his or her physical form, when in fact the two things rarely have any real connection at all. The women who cry out against sexism are guilty of this too, by the way. They make judgments about other women all the time.
In the case of Bayonetta, the cries of "sexism" often seem to come from people who are trying to convince themselves and others that they're sensitive enough to understand sexism... probably so that they can get laid. The little bit I've seen about Bayonetta suggests to me that its sexy heroine isn't promoting sexism in the slightest. From what I can tell, some might even make a reasonable argument that her fantastic appearance helps to fight sexism!
"Too often we enjoy the comfort of opinion without the discomfort of thought." - John F. Kennedy on reality
"What if everything you see is more than what you see--the person next to you is a warrior and the space that appears empty is a secret door to another world? What if something appears that shouldn't? You either dismiss it, or you accept that there is much more to the world than you think. Perhaps it really is a doorway, and if you choose to go inside, you'll find many unexpected things." - Shigeru Miyamoto on secret doors to another world