We have been talking about this for a long while. We are looking for an effective compromise between removing Sigs all together, disallowing Signature advertising, allowing signature advertising, and allowing you to advertise your own things.
I still think allowing signature advertising, but basing payouts off of activity is the way to go. That way it leaves signature advertising for those who dont abuse it, it makes it so spammers only need to spam 7 posts per week for maximum profit, and it allows people to keep up signature advertising if they want.