@WTFE I was not referring to the existing server bases, but rather the emerging ones like Evennia and Ares that are attempting to incorporate new technologies and paradigms. Sorry if I misunderstood your point; this thread seemed very Evennia-centric.
That said, I would argue that command-line interfaces like Linux/Powershell have not made the sort of stunning "foundational changes" that you're alluding to. MUSHing is, fundamentally, a command-line interface.
Now if you're talking about changing that fundamental foundation, groovy. But as I mentioned, that requires not only a server-side change, but a client-side change as well.
Personally I believe the server should come first. Once you have a server baseline that isn't using 1980's tech and a bizarre variant of a long-dead programming language, you can start talking things like: "OK, how can we extend that server to do cool new things with new clients while still supporting old clients."
I'm not trying to be Steve Jobs here. I'm just trying to take that first baby step.