> Why should I write a review? I have nothing to gain.
Unfortunately I'm now of that mind-set as well.
A few years ago I was in the top-500 of reviewers on Amazon UK, based on 'helpful votes'. I only reviewed things that I had bought for myself and focused on items that had no or very few existing reviews.
Then two things occurred quite quickly:
1. I learned that many top reviewers were receiving free samples as part of Amazon Vine. I asked myself: why am I spending my time doing this without recompense? They were churning-out multiple reviews per week and I was doing perhaps three or four a month, but it still felt unfair.
2. People starting aggressively scoring reviews negatively for subjective reasons. I remember an airline stewardness marking as 'unhelpful' my review of a book because she said I had insulted her airline. Amazon weren't interested in reverting down-votes like that.
I drifted away from Amazon reviewing after that and in time I have also drifted away from Amazon. They never fostered their community of honest-amateur-reviewers ( with, say, a Gift Card at the end of the year ) and they're paying the price now.