Look at this problem from the perspective of someone who just joined. "Contact administrators" sounds prohibitive to new players. I would expect an option to rename myself to be under "Account maintenance". Not there... Between "Should I bother bother admins directly?" and "Let me ask the community", the latter usually seems like the better solution.
The FAQ already had this:
I forgot my password/username. Help me pls!
If you forgot your password/username please contact one of the server admins to receive your password/username. They will reset it to something and pm it to you.
It's not really about renaming, but close enough. Someone who bothers to read the FAQ would see that this is the preferred solution, but there's no mention as to how
to contact the admins. How many people read the FAQ before posting here is a different matter...
More importantly though, I don't think putting it up there will change much. A technical solution that I see is to have a button on the profile page that explicitly says "Apply for a name change" and does the same thing as "Contact admins". And maybe even the in-game profile page. Because if it's not very discoverable, it will not be discovered.