I've only interacted with one teacher on the issue. It's seems to me she didn't like it because it was creating more work for her.
I hear the same thing from teacher friends. Much of it is caused by silly, bureaucratic requirements and mind-numbing record-keeping, Teaching to the tests is another big complaint. Part of this is due to the local administration which is so PC that all classrooms in a grade level must be arranged the same and teachers must make home visits to parents who won't come in for teacher conferences.
Needless to say, the turnover rate for teachers is astronomical.