Why not allow free access?
I think most people would agree, it's hard to find quality in free stuff.  Anyone can create a training video and post it, but it's hard to find good quality ones you can actually learn from.  In addition, opening up the forums and video requests to the public means anyone, including those with malicious intent, can post and make requests, which does not help the community.  I think people are already tired of spammers, and would prefer not to deal with them.  Subscriptions help to keep them out.