From the viewpoint of one of the legion who hasn't written (well, published) anything and tends not to review (sorry guys~) I find it difficult to actually express myself in a review.
There are so many stories that I've read that were good; it's just that nothing really caught my eye enough to comment on. Most of the time when I want to comment, I've only got something critical to say. A lot of people take critical reviews very badly and start complaining about being flamed, even if you really didn't write it with bad intentions - so I just don't leave those kinds of reviews if I like the story for fear of the author taking it the wrong way. Also, I don't find much point in leaving the one-sentence "omg xxx is so funny update please" reviews.
So it's all added up to me saying not very much at all :/
I think there's a lack of constructive feedback, not because we generally dislike your story, but because there's this whole sense on the site that unless the review is positive, then it's worthless - a troll, a flame. Please don't take a lack of reviews as a bad indication because yes, the bad things are much more likely to catch the attention of the reader than the good things, but if we're not pointing them out to you that probably means we don't want to discourage you.
There are the few, the brave, the constructive reviewers like megadeath425 above that have overcome that inherent shyness, and we salute you. But it kinda does seem from your post that you're not taken seriously despite being exactly the kind of reviewer that most people claim to want, which I think is a sad reflection on not all the authors, but enough of a minority that has ruined it for the rest.