I think that there's a market for both styles. I very rarely play any text-based stuff, even though I've just created my own as a programming exercise, and I prefer a more sensory feedback from my games. But there are plenty who do play text-based games.
It's much like the book vs. film market...
With a book or a text-based game you need to be able to visualise many aspects of the environment in your head. There is more room for creating richness of story and adding in character and backdrop to your game and the entities within it, but then you usually can't provoke such intense momentary emotions within the reader/gamer than you can when someone watches a movie or plays a more graphical game that they have immersive control over.
That also is another aspect to the reason why text games are not considered mainstream anymore: the interface either promotes or limits gameplay. This is the reason why text-based games tend to only be in the RPG genre - you can't really control a car through text and feel like you're driving, you can't shoot at someone and feel like you've survived anything, and you can't build something and stand back and look at it.
A movie (or TV show) or a visual game is, as said, more intuitive as there's simply much more easy to process feedback and environmental awareness. As there's less work to be done to get around the business of actually controlling and understanding the game it's just easier for the vast majority of people to understand and therefore prefer these forms of media. Even a lot of my friends don't read books for fun nowadays.
Also, although web-based games, etc, are doing some things to change this, it is only really a more hardcore element that will play these games anyway. This guarantees that the audience that is there are all keen and appreciative, but many casual gamers could feel they won't get anything more out of playing one of these games than reading a book. And many casual gamers could feel it a waste of their machine's power to run only a text-based game on a modern PC - why not just get Oblivion and really enjoy the graphics/audio/AI/interactivity that the text-based game won't be providing them ?
When I say "casual gamer" I mean someone not hardcore into games - more a stick-to-the-mainstream gamer - rather than the more games-related expression of someone playing things like web games and mobile phone games a lot.
I'd say you'd be well in the minority in preferring text-based games (even on a highly specialised games-related forum like this) if you ran a poll on this thread. But that certainly wouldn't make you wrong for feeling that way. Storyline, depth and great dialogue are always commendable. Now we just need to get them into a quality FPS game and really have some fun :sneaky: