My acting coach really loves improv. Why?

I really am a give me the lines and direction and I'll go type and really do not find a lot in doing excessive improv. I actually got visibly annoyed as I just couldn't think up another random activity while digging an invisible hole in the ground. I feel like I'm coming off as a fool rather than exhibiting what I'm actually good at. Yeah I don't enjoy improv. Am I alone in this?