@Tekkub & littlebuddha79: I agree with your answers to my post, I didn't elaborate because as I said, I didn't want to go off-topic as it belongs to another debate.
Come to think about it, maybe such criterias would be worth being displayed if the rating is set by a "committee" of guys who can make an educated judgment on the quality of addon. I'm ok to hear that the quality of my code or of the structure of my db is only worth 3/5, but only if 1) I know why, and 2) that rating is given by someone who really knows how to judge based on measurable criterias.
I would hate to be judged on these points by non IT-literate users. I would, however, appreciate the feedback (and possibly rating) of non IT-literate users on things like user friendliness, ease of use, etc... But this feature and the previous one are actually roles that are partially filed by a forum, as these issues are more likely to be addressed by a constructive debate rather than by a simple rating.
It's a tough choice to decide how to effectively address this problem if you ask me