I think you just re-invented play-by-(e)mail roleplaying. (and SpellMaster) :-)
Well, yes and no. And SpellMaster was a significant part of the inspiration for the idea ;-)
The difference would be that the players can look at the map any time, and the computer can keep track of everything that's happened, both the text of everything people have said, and the record of where they've all been, etc. They could even look at the party members who are currently with them, see what they're carrying, etc.
The problem with this is that you lose one of the most important tools of storytelling: Pacing. You have to make it up somehow. In SM I had something, for a D&D thing you'd have to come up with something.
Yes, I know, that is the main problem, and I haven't yet been able to come up with a way to make up for it :-/
But I guess the question is: is it an acceptable sacrifice to make to be able to play D&D with a bunch of people who are, in all likelihood, never going to be able to come up with a single time when they can all meet to play, even over the internet?