I think there is a desire for things to be permanent, yet so much that we treasure is made even more valuable by the knowledge that its not forever.
I'm toying with the idea of a communal art-project for ourWorld, that allows players to cover up the work of the previous artists, or if left too long, vanishes with time. I love the notion that players could impact their virtual world, if only for a little while. It's just an idea, and I'll have to do some convincing to make it happen. It's not technically prohibitive, it can be monetized, and it's pretty fraking unique. Fingers crossed.
Speaking of Transitory. Here's a clip from my last robot fight. My robots were the losing pair.