Well, Jug, while most of the nitpickers are not modders, there have been instances in the past where they were. The "mod wars" that have been waged have been ugly and are usually even MORE out of line than the statements from the non modders.
So the caveat is while maybe you HAVE done something as good or even better than some particular mod, that doesn't give you the right to denigrate someone else's. Helpful criticism along the lines of "if you do X you would probably not see Y problem" is fine, but when it goes to "how can you release a mod with Y problem and call yourselves quality?!?" it just becomes ludicrous.
It seems to go with those who create, though. Musician A will ridicule musician B, filmmaker X will cut down filmmaker Y, and so on. I don't understand it, but I recognize it's not limited to mods.