As it stands, we are at a fine balance on allowing signature campaigns and controlling spam on the forum.
If we're to swing ay way, I'll suggest we go towards more regulation for spam and this is a community exercise, meaning if you report posts that are off topic or redundant, it will help the mods to find and delete them.
I personally think the forum is better off with signatures, sure it is an incentive to post and some of those posts might be forced or repetitive, but a huge chunk of them are educative and helpful. Most of what I have learnt from the forum were from users who were wearing signatures. Removing signatures will also cut down on educative posts as well as spam replies.
I agree; although I understand the OP's concern, regulating spam and removing users that repeatedly ignore the rules is what's best here. I was here before the merit system was introduced; you should have seen how much spam there was. Everyone could simply rank up with the only requirement of being active and posting; it didn't matter what; just post whatever comes to mind. A large number of those users have now quit because they weren't able to participate in signature campaigns, while the merit system discourages spamming newbies who're simply after signature campaigns because they have no chances of ever ranking up.