Custom titles are fun and pretty standard for forum communities. They're nothing substantial, but they add to the user experience. I can see how it could be abused though. I didn't even know they were disabled, I was sort of looking forward to reaching the previous required post count.
As for username changes, I was a little surprised when I discovered you could change your username on here and that you could do it so freely. A username change can be confusing, but I guess that in itself isn't too harmful. This is just me, but I wouldn't want to do it. It seems strange to build and invest in an online identity within a community and then change it. I think having to PM an admin would be the best and most safe way of having username changes.