I have had a few thoughts on this as well, although I don't post many reviews. For one thing, I don't have the time. But a reviewing system, to be useful to me, the reader, should be like measuring scales--which is to say, honest.
If the practice is for everybody to not give one star reviews, then the reviewing scale is effectively reduced in range to four stars, and then the two-star review becomes as 'awful' as the one-star review. Not that I think people will pay much attention to that pathetic suggestion.
A reviewing system is there to serve the READERS, not the writers. Writers have their own agenda, which is to support other writers. Not that there is anything wrong with that individually, but institutionally it weakens their credibility. Somewhere there was a comment about supporting living authors, and I thought, "What does an author's status have to do with a reader's needs?" I'm not the only one who has noticed. Publishers now report that back-cover blurbs from other authors are almost useless. And you can add aspiring authors, who measure their words against what may one day be said of them, to the list of 'those who are not likely to be fully honest about a book'. Expecting an author to serve the reader's needs in a review, instead of their own group, is a conflict of interest.
Of course, I write too, and I know the feeling in the pit of your stomach when somebody doesn't like your work. But those are the most helpful reviews I have received. Many people who don't particularly like what you write won't give you specifics, so you can't improve.
For the record, I tend not to believe five-star reviews, either. When I talk (email) to people who bought my work, I usually told them, "If you feel like posting a review, then for God's sake, don't give me five stars. Those always feel like fakes to me." A few did anyway, and I have to say I wonder if they would really tell me what they didn't like, or if they are more interested in appearing friendly.
But then, I'm a storyteller, not someone who is trying to make a living at this. I'm more interested in really entertaining the few people I know, and seeing the result, than in chasing down commercial success.