Dave rants and Scott ponders about walls. I agree that walls are not fair to everybody, particularly to those who find themselves not within the walls, and that increasing popularity of invite-only events and services is not healthy for the community as a whole.
But I think walls are like security blankets. It's not about reasons but fears and wants. It takes courage or recklessness to let them go. Frankly, I think it's foolish to let go of the blanket unless there is either a big carrot or stick hanging over one's head.
When in doubt, think like a pig.