In 1.8 there was the ability to throttle registrations by 1. Setting how long a nick must be connected before issuing the registration command and 2. Limiting how often the registration command can be used. Set #1 to 30 minutes, set #2 to 24 hours. If users complain about having to wait so long, they likely aren't that interested in the long term anyway .. just sayin
If this isn't in 2.0, it should be.