Take from it what you will. Unlike other actresses in her age range (Demi Moore, Julianne Moore, Diane Lane), Marisa seems to have lost a step or two along the way and has been willing to show more skin in order to keep working.
Demi Moore (Striptease), Julianne Moore (Boogie Nights, Chloe,many others), Diane Lane ( Unfaithful ), You were saying? Just because an actress shows a little skin does not necessarily mean her ability to get good roles has diminished in any way.
She has been quoted "[on being nude in films] I definitely feel like I didn't want to do that kind of thing when I was younger because I didn't think that it was something a serious actress would do, in a way there is validity to that. It's harder to be taken seriously when you're younger, doing that but I've also come to a point of being able to handle the reaction to it - that probably would have been more difficult when I was younger".
Also she was nominated,and won, for numerous awards for her roles in "The Wrestler" and "Before the Devil Knows Your Dead", both of which she appeared nude in.
I think your just jealous she looks better at 46 naked than you do.