MrP. Yes.
The exploiter could hop on the server while no one was on, grab all the ulx log files, then leave and peruse the logs over past <x> hours and every IP would be there.
Storm, I can change my IP quicker than I can my SteamID. 1 minute for a router reboot, and it is often in a totally different range (ie, if banning me, you couldn't use a x.x.x.* ban)
(Then again, I don't have more than one Steam account)
If I did, changing my IP would only be about one minute longer, depending on Steam sign-in time.
I understand feature vs safety. Speaking for Megiddo/SticklyMan's latest code session, I believe they just decided it was safer to not have it, considering how easily volatile an IP address is.