A far cry from the virtual worlds we know today, yes, but that's where it started. CG actually focuses on the higher level of things (in many MUDs, players could actually form guilds, and wander around the world together-- "go north"-- killing dragons-- "attack dragon with great mace"), but even the most basic of MMO thrills was originated in the MUD world. "Seeing" a virtual character pass through the room you're in ("Kingofworld enters the room. Kingofworld leaves the room.") was a thrill, because you knew that there was someone else, looking at a screen just like you, behind that character. On the other hand, as CG points out, there were a lot of things that MUDs could do that graphical MMOs can't nowadays.
One of those things is simply the level of interaction between the devs of the MUDs, and players. Because the interface was so simple, devs could change the rules at will, and even give some players the ability to change the rules themselves. Devs could interact with players nightly in game, and even destroy or recreate entire sections of the world just by changing a few lines of code. The game asked a lot more from players, of course-- playing a text-based game is entirely dependent on how willing you are to use your imagination to "see" what you're actually doing, but because the overhead was so simple, the worlds were that much more involving.
Visiting the Hinterlands at sunset in Azeroth is beautiful. Seeing nebulas and astroids in low sec space is really pretty. And MUDs, for all their popularity way back when, can't offer those kinds of views (unless you can imagine it from "The rust-red sun sets behind the mountains and reflects off of the sweet smelling pines as an angry Owlbeast advances towards you..."). But they do offer today's game developers good ideas on how to bring back the old fun. The goal should be to create a high-budget graphical masterpiece that has the intimacy and ease of those old text-based dungeons.