I agree with just about everything Capt Pprune said. However the last few posts are a bit worrying.
I am not a pilot but work in ground ops. The big issues effect me as much as they effect pilots. While I agree totally that gossip, name calling, libel, abuse etc is not to be tolerated, and that abuses of anonymity are also to be clamped down on, I feel the forums are best served by being available to anyone, pilot or not.
A charge would reduce the number of subscribers and contributors and probably leave only pilots.
You guys need to listen to alternative voices and opinions sometimes, and remember that you are one part of a very big team. You may get the stress and the responsibility, but you get the rewards, and without the rest of us you'd lose the lot, and vice versa of course!
This is a great site, important to the whole industry, and maybe a better protection would be to restrict more forums the way the private airline forums are run. Prove your relevancy to the industry and get in. And if we continue to abuse it, then I guess we've blown it for ourselves - stick a charge on and we'll leave you alone.