While they are free to join the channels, I'd imagine a great deal of the users authenticate to the nickserver to avoid impersonation and to protect their nick.

While they are free to join the channels, I'd imagine a great deal of the users authenticate to the nickserver to avoid impersonation and to protect their nick. Without SSL, anybody on their network could potentially sniff their credentials with a lot less trouble than MITM'ing a SSL connection. So I'd say that it's just not for the 2% that are using the secure channels, but probably for the majority of the userbase that is active for more than a couple of sessions.