If you want the ability to wear a signature, purchase a copper membership.
Don't encourage newbie to buy copper membership in order to wear signature. They will spam over forum and this topic is a example.
That's just an another way of thinking, but there are some net positive effects to the forum if a user buy a copper member account, it affects the BTC storage and income of the forum which can be later used in the betterment and spam management too.

I think there is nothing bad in promoting the sale of copper membership.
This really a good explanation for making quality posts.
+1