Just like every other thing, there are good and bad sides to signature campaign since it introduction to the forum, I wasn't here before signature campaign got introduced but I was around when it become more popular and the good thing I noticed is that it help improved many users quality but also the spams were in their numbers but still many users had to work on their accounts to be eligible for acceptance into campaigns and ironically it also improved the quality of discussion we got. There will always be bad eggs so lets not use them to disqualify the impact signature campaign has brought to the forum.
Every platform out there has one way or another that they're rewarding their active users and the forum doing the same is encouraging. If the signature campaign aren't harming the forum then they don't have to end but if they're causing a nuisance and it's becoming uncontrollable then they can end it. The signature campaigns are just privileges as what is important is the discussions we're having on the forum. The forum interest should always be put first just as how theymos had to end all mixers when their presence on the forum were becoming a problem, same can be done for all signatures.