Unless you're testing for bugs or other such issues I don't see any need for such negative criticism or "give it up" type of comments. An individual mod is not like a MMO update/DLC, it is not required in order to progress further or to complete the game -- it is a privilege that some modders take from their free time to invest into adding something fun & new to the experience. If you just don't like the mod because it's not something YOU would do then by all means step out and make your own, no need to rain on someone else's parade simply because you dislike or have low faith in the person's modding skills.
Constructive criticism is entirely different -- if you played through a mod and noticed issues with it, or maybe there was something about it that you think could have been improved upon then that is where the pos/neg feedback is essential as it is not only helping the modder but is also helping to get the mod fixed and re-released. That's my 2 cents on the subject.