I consider Lauda to be a fairly reasonable person. If a person improves their post quality and consistently post that way I see no reason why they wouldn't remove the negative trust attached to the account (as it would no longer be valid).

Who do you think would do the work? The only person Global or above showing any interest in cracking down on spam on the forum is hilariousandco, and a task as widespread as cracking down on spam cannot be done by just one person who already has other responsibilities.
People are getting tired of the mindless spam all over the forum, as I would think you are. Negative trusting these users to prevent them from joining most campaigns is a good method of attempting to lessen the problem until the mods/admins show that they care at all.
It is getting past the point of it being acceptable. People are joining here specifically to join a signature campaign and spam shit for some coins. That isn't right.