Brotherhood, don't get me started on syncing several game-servers, I have been doing that for several years now 
Going into the subject why one does NOT ban by subnet or even IP (hint: dynamic IPs) to hit a lone player and why one does NOT sync bans by guid would be too much for this thread. Look up the different topics about it here.
And YES you do have actually and positively to identify a player to block him/her.
I really don't understand why you care so much about this. Just becuase you don't have a use for something doesn't mean no one else does either! WHY did I add the banned tab?
1. I had it already set up nicely in memory
2. I had an easy framework to copy from the Admin Config tab
3. I thought "What the hell, I already have everything I need, might as well do something with it"
The banned players tab does not ONLY add banned players. In fact, the first version of it could only modify the CURRENT banned players info (time, reason, etc). The add function was just implemented to make it more complete in case that one time you need it, you have it. Not every single function of a application has to be ultimately usefull.
And funny you mentioned "Syncing Several Game Servers". That was my next idea for TSM. TSM Remote Control (over TCP/IP), alowing you to have one master TSM and then each server run a child TSM that updates it's own configuration settings through the main server
