Constructive criticism is fine. Occasionally expressing more generalised and unconstructive negative opinions is fine.
However; some posters here feel the need to post almost nothing but unconstructive moans and negativity. This adds nothing to the forums and gives nothing back to the Larian team that they can take onboard for possible changes.
The tone of your posts affects the tone of the forum, and one of the tasks of the moderation team is to maintain a certain atmosphere. If this involves removing a poster's right to post then it will be done.