In Bayonetta the cheesecake actually serves a purpose. The boiler plate is that she's a woman that displays some kind of sexuality plus she's a witch killing angels with BDSM moves while fighting church who don't like either of those things blah blah blah standard explanation.
But more importantly is that the cheesecake is part of the comedy, Bayonetta is a really funny game just like the DMC series where you laugh out loud at certain points. At least I did. Dante getting an electric guitar in hell that shoots lightning bolts then doing a butt rock solo while stage fireworks go off isn't a cool moment, it's a hilarious moment. Bayonetta is like that as well, the nun intro actually made me look over the shoulder hoping that no one would walk in and see me playing it, even though I was alone in my apartment. The twist is that the sexuality in the comedy(cutscenes) is intentionally uncomfortable and cheesy to the player, it's not erotic in any way in my opinion. It really, really hams it up. Again, just like DMC does with its cool factor. Both of those series are cheesy as fuck and really funny. Raiden running around Arsenal Gear naked while cupping his dick and balls is more sexual than those two games combined.