@faraday True, and I agree.
But for UI, we're behind the 8-ball. Iron Realms who made the comment about 'the first wall of text is a turn-off' use some pretty fancy interface.
The top right is chat/channel window, below that is a map that can be clicked on to navigate, click a room you've been to and you autowalk there (autowalk isn't know, MUDS use aliasing to make quick commands much like some older MUs have done). Click an arrow and you try to move/walk/go in that direction. No need to type an exit or direction name. Those images at the top are quick commands for abilities. On MudClient app for smart devices, one can change buttons, its not hard to have a 'who' button that lets you know who is on line. I've seen text data bank scroll wheels to get to common command like tell or pose even, I've used MUDClient to Mu before All that character information stuff on the left could easily just be sheet and finger notes. Enemy information could just be IC info on another character who's name you click on.
It could be super slick, and has been seen in MUDs already. The comment about hitting the part where reading comes in still rings a bell with me of curiosity. Also, learning different page commands isn't an issue for younger audiences, if there is a will there is a way. Various MineCraft servers use a few different ways for communicating personally, because like MUs, there are different systems once can install on their server for communicating.
I'm sure there is a happy medium somewhere certainly. But in the same vein, introducing a Mu as a text based environment where reading and writing is required like upfront could also help, part of the advertising/image. We've known for years that some of the folks that wander in from other mediums start with like RP'ing on WoW or EverQuest or whatever MMO and the RP isn't enough for them and they found MU's. As much as 80s interface isn't for some people, there still needs to be an input for text to write into and an output to read what is going on.