I am a chauvanist! Mmmmmmm boobies!
But there's more to it than that. In fact I once championed feminism in videogames quite heavily, and I'm still all for it. The other reason I like the PD0 design better is because it takes a step further from reality. They could make her flat-chested and short-haired, as long as she's less realistic than before, I like that. Visually, I find realism dull.
I have some tiny guilt because I agree that the old design was one of the best, most realistic designs for a female game heroine, but I'm not going to pretend that I like it better just because I know it was morally superior to her new design. I like cartoon hotties.
I also like variety, and I hope Rare continues to evolve the design on Perfect Dark when it makes another sequel. Edit: I'd also say that I hope Rare makes the next Perfect Dark a better game, but as long as they suck, I don't have to buy an Xbox.