My issue with Greenlight is that a great deal of the games on it are so underwhelming. I was expecting a ton of fresh, interesting ideas, but everything looks like I would lose interest after playing for an hour or so. I just want to be wowed again...
The thing is if a game is that special that it creates that kind of feeling and is that fresh it shouldn't need Greenlight in the first place.
And this is why the other games get upvoted, because people think like this.