[camlorn]

Firstly, an audio-only mud, a "sound mud", I'd have to go with no. The whole point of muds for the blind, if you ask me, is that it can be shared with the sighted. Also, with the right setup, and with text to speech being what it is, it is possible to already get a voice of the quality required for "telling a story". Most of us don't, but it does exist; see the Nuance voices for NVDA, for example, or Siri on your iPhone. None of us seriously use those, though, so far as I'm aware: things like Espeak or ETI Eloquence are robotic, but intelligible at 400 words a minute plus (I'm not exaggerating here).
Scandum, most blind people I know don't even know how to bot. Most blind people I know hear the word trigger and go catatonic in horror, or something like that. I think that you are drastically underestimating the capabilities of a blind player. The spectrum varies widely. One advantage is that text to speech, if you train yourself to it, can be 400 words a minute plus; one disadvantage is the lack of skimming. Our comprehension isn't somehow "less". I have my idea of what a fireball is-in my case using what I can see of the world. For those fully blind, I imagine an apt description is a graph of things that relate to other things; I can see that a fireball is big and bright, for example, but don't have a clue what most common animals look like. I know what they represent, however, and that is enough for me to write about them, let alone comprehend your writing about them. I'm not sure if you somehow think that a blind person gets less out of the same words, or if it's something else. Consider, however: some of the top Godwars2 players are blind, some of the top Achaea (can't recall proper spelling, sorry) players are blind, and apparently at least for a period the highest level player on Materia Magica was blind (I don't know if this is still true, and don't know them myself). Please, explain what it is that you think blind players can't comprehend, or what specifically blind people can't do on a mud.
And, addressing the moving pad comment: see refreshable braille display, omnacon (discontinued in 2005, haven't used one myself), and the new generation of touchscreens that are promising tactile feedback (or not, no one's built a tablet yet). In general however, text to speech goes ridiculously fast. By ridiculously fast I mean faster than most, if not all, sighted print readers. I will meet someone who can come up one day and understand my computer, I keep telling myself that, but it hasn't happened yet; as you improve your reading skill, we can choose to improve our listening skill, and the nonscientific evidence I've seen places the rate I can achieve (and have achieved) above print reading in general. I am faster than most; I chose to treat it like exercising and systematically turned it faster, but some are even faster than me.
PS: For the record, I don't have enough vision left to help me with muds in any way.