accountability, tracing the leaks.
If you have a popular server you are going to have lots of admins, and you may not even own the server(you are just root), inevitably many careless people will end up with the rcon password
When someone from an unknown IP connects with the same rcon password many others use and bans everyone, its hard to take corrective action.
server.cfg:
rcon_password_clear
rcon_password_add "pass1" "bob"
rcon_password_add "pass2" "john"
server log:
rcon 123.123.123.123 bob: status
rcon 123.123.123.123 bob: say hi
rcon 223.223.223.223 john: status
backwards compatibility:
keep rcon_password
authenticating from 3rd party tool will be the same, except there will be multiple valid passwords
hardening:
don't let rcon contaminate this feature (this may conflict with a rcon can do anything philosophy)