Basically I have never written an app store review - and I think that means the first one is a hassle. I suspect most people are in the same boat and when faced with a form to fill in before you can do a quick review will move on to something they care about more.

I just wanted to suggest that despite a relatively strong motivator - I don't complete. So my motivation may be an outlier but I suspect my experience of "eh, can't be bothered" is less so.