Because that has to do with her and her fear of hurting people. At least that's what I think.
The first time she used her powers she put a boy into a coma, and after that she didn't really use her powers unless told to. So it's not like she's Jean and could say.
"Hey you mind if I practice my powers and go into your mind?"
She ~has~ to hurt people in order to learn to control her powers. In my theory