I understand that people were desperate to create a character on any server but most people, deny it though they will, knew that they couldn't freely transfer from legacy to non-legacy. If you created a character on a legacy server, you knew what you were doing.
To be honest, if you created a char on different servers at all, you knew the risk. It's very nice of SE to allow server transfers like this, since it was their "fault".
However, yeah, transferring between data centers, even if a special one-time process, should be designed and permitted. (Make the application, and a dev does it manually sort of thing, even if they never offer such a service again).