Sure women want to hear dieting tips. They just don't want to hear them from their boyfriends.
The problem is, that Microsoft ended up doing this in XP as well. And it alienated its existing user base. I still know people that want the "Classic" start menu set first thing when XP is installed. It's change for the sake of change. Except I notice that Vista's UI is a much more redical change for a much more negligible benefit than 2000 -> XP was.
If it was really better, it wouldn't need to be designed from scratch again every release. Even if the excuse is to make it easier for new users, how many new users are you going to pick up in a market that's so saturated and that you have such a large market share of? And how many of them are really going to make their decision based on what's new in the latest release of a product that they don't know anything about in the first place?
I have a theory that it's impossible to prove anything, but I can't prove it.