Honestly, I think she has more of choice. She could take smaller parts in indie films. I am sure she would get offered them if she auditioned. She is a celebrity and would get a smaller film some attention.
My sense is also that Kristin is a comedian and very physical. I think she chooses films that are meant (on paper anyway) to showcase her comedic and character acting abilities. She has worked with some big names actors and that gives her much more power, especially if she makes connections with them and becomes their friend. She is friends with Robin Williams now-don't tell me that is a bad thing in Hollywood.
Plus, she will make more $$$ in a big budget picture even if it flops.
The same fate seems to have be-fallen the uber-talented Kristin Davis of Sex and the City. She seems to be typecast playing old men's wives in Disney films. She deserves much better, but I am sure she is happy to be a working actress on big name projects.
Both women can take projects with healthier paychecks in order to make more unique professional choices in their down time. Like she made 2 big budget clunkers and then got to do Running with Scissors which is more indie.
"The sexual energy between the mother and son really concerns me!"-random woman behind me at Next to Normal
"I want to meet him after and bang him!"-random woman who exposed her breasts at Rock of Ages, referring to James Carpinello