I do, all the time. I love pitching concepts and ideas, but then when it comes to enacting them, it's like, "Is this readable? Are my ideas getting across? Am I matching my partner's writing level?"
Letting someone see your ideas - especially your loose, vulnerable ones without much prethought - is scary. But at the same time it's exhilarating when they latch on and roll with it. So it's worth it!