Uhoh, lets not get too politically correct here, people do need to express themselves sometimes, and if something is bugging them big time, its better get them to put it out there so at least others have a chance to fix things.
Myself, I would rather know the good and the bad about a product, so I can make informed decisions about when to use it and when to use something else, and would suggest that devs need to konw this also, so they can improve things.
I do not believe that only saying nice things for the sake of saying nice things is a good thing, however any personal attacks on a person most certainly should not be tolerated.
Getting frustrated when you are you are trying to do something and it just wont work for you is a normal human behaviour, and if expressing that leads to a negative post, that then leads to a solution, or draws attention to a problem that needs to be fixed, well, that is what a forum is for is it not, a place to discuss and resolve things?
I could be wrong, but I dont think the intent of a forum is to produce a fanclub, ie, there is no team cakewalk mearchandise store or coffee mug and lanyard promotional giveaways :)