As for another reason....
Certain IRCds allow for channel ops (or others) to use RAW REMOVE, which will force a PART command. Currently, mIRC will close the channel whenever it receives a PART command for the current user and it wasn't after the user did a /hop.
As for other situations, a delayed /hop script could be made with this, as well as changing nicks when on a +m channel (on a daemon that suppresses nick changes when muted). Both of these have already been suggested, but they are worth mentioning.
