Yeah, the Evolution demo ED gave earlier today.
I watched it and I don't remember anything about it being mandatory. The user accounts are trading addresses in order to send transactions. Why couldn't you just send to an address without using an account?
The whole third tier is designed around having some sort of pseudonym on the network, so yes to use Evolution it would be mandatory. However, nothing is really finalized at this point. I'm still really early in the process of designing the system. Was there some problem with have a permanent pseudonym? If it were mandatory, that would mean you couldn't use evolution without an account on the network, but it doesn't mean anything you do on the network with that account would be identifiable. It's just a means of connecting people who want to be connected basically.