(Since I've been warned I will only discuss my personal opinion on what I think passes for useful threads)
I think discussion and discourse and arguments are perfectly fine, but there's a difference between making a post called "My reasons why I don't find WoW fun anymore" and if it's fully thought out and well written, versus a post "this is why wow is dying" and listing one issue that is subjective as though it were fact and is the only reason wow is struggling. One way leaves it open to interpretation and rebuttal and discussion. The other shuts down all discussion by implying that your pet peeve is fact and is a broader issue than it really is.
Most people are convinced their feelings and opinions are the only ones that matter and that's why certain threads are useless when they encourage arguing opinions rather than discussing them. There's a way to handle disagreement without turning to negativity.
Even if you think WoW is terrible and has nothing good left to offer, not everyone feels the same way. You insist that it's the "reality" people are fed up but it's not necessarily the truth. This is exactly the type of argument that breeds only negativity and has no positive merit in a mature discussion