Another trend you will notice is that... I'm sometimes the only person to rate a mod. If you think a mod deserves better (or even worse), then you can be the one to push them in the direction. Ratings don't change without some support.
And I usually stay neutral on addons unless its something I really like or dislike, or something that leaves a strong enough impression (one way or the other). I can't give a proper review on everything, but I like to give at least one rating as a "first impression" sort of deal, and say "Welcome to releases!" like I used to do back when they were forum threads that needed to be bumped with some form of post. I usually leave proper reviews up to others. Still, one "first impression" rating is better than... absolutely nothing at all.