Cost per action/sale methods require that referred visitors do more than visit the advertiser's website before the affiliate receives a commission. The advertiser must convert that visitor first. It is in the best interest of the affiliate to send the most closely targeted traffic to the advertiser as possible to increase the chance of a conversion. The risk and loss are shared between the affiliate and the advertiser.
I would also like to see a forum built into the platform. Wealthy Affiliate has a unique way of building a community and I understand why they shy away from a standard forum type of format. Instead, they want to promote live chat sessions, blog posts, private messaging, and public questions where people can comment below. This type of setup is pretty cool at times, but I also do enjoy forums where I can just browse by topic.