For me, it's not a matter of humor; I find myself less satisfied by movies (and TV shows especially--not to mention infuriated by all the commercials) in general. We have been out to a handful of movies in the years since DS was born, and each time I felt like, "that wasn't as good as I wanted it to be." When we see TV at my parents' house, I just stare with my mouth hanging open until I snap out of it and leave the room.
I think that, as homefrontgirl said, now I know there are other, more satisfying things for me to do. When I feel overwhelmed or tired, I crave the "vegging-out" aspect of seeing a movie, but when it's over I feel like I would much rather have just gone to bed early.
(Strangely, I feel the same way about sweets now that I've stopped eating sugar. When I do eat something I used to love, it doesn't taste the way I expected or wanted and I end up thinking, "well, I won't try that again!")