It solves the problem (...) Unlike a password, these aren't things that can be tossed about unless you have a photographic memory.
I think we must not have been talking about the same problem.
I wasn't talking about the strength of passwords vs. strength of key pairs. Besides, a password can be made as secure as a key pair (insofar as sending something to a perhaps untrusted MUD server is secure to begin with) by just having a very complicated password...
But I'm not sure why you say that keys can't be tossed about just as easily as passwords. Here, let me paste one:
Well, you get the idea. Perhaps you are speaking about bad passwords like "hello"?
I suppose, although it would still require the end user to run their client inside another client (which would do the authentication and ssh protocol layer). Not something I'd expect to see often.
Well, I'd just tunnel locally as well and not use any dedicated client. But that's basically running in another client, yes.