I don't want her to go either, but you have to understand that there would be characters that would want to choose something else for their careers (like Grissom) as well as they would like to be promoted (like Nick's case). I don't know what is Willows' case, but I'm sure she's having second thoughts about being a CSI. She's away from her daughter, she's made many mistakes and she has been demoted. So I guess, we will know her reasons soon.
Don't you think?
I like Brody, I just didn't like her asking if Nick was seeing someone

after noticing Greg likes her.