These people are weighing in with their opinions in the discussion. I think the pessimists weigh in because if they don't then people will confuse the optimists as being the majority opinion. It's important to have representation of the counter arguments so people don't go along their merry life thinking "everyone thinks this way". It sounds like you are "the pot calling the kettle black" right now, due to the fact that you're whining about the same thing, just on the inverse side. I understand your frustration, but they feel the same thing on the other side of the argument