How it should be: when the server is 75% full (or whatever number <100% that might be) the server gets greyed out. But anyone on that server can send a code to a friend that will allow them to create a character on that server. Problem solved. I don't see how this could have been missed, especially with the description on the character select about playing with friends and not being able to move once you select a server.

SE PLEASE RESPOND!