I have been mudding for 11 years or so and still enjoy it. I find that even though you do not have the pleasure of graphics there are other benefits.You have the pleasure of real time interaction between players. The worlds can, and usually are, huge with 10,000+ rooms. It is easy to learn how to design your own areas thus everyone can add something creative to the game. Pending on who the owners and how much they know about coding there can be alot of additions made to the game play.
I do believe that there are alot of games out there that are more desireable but as far as role playing games that will be around for a while these the best that I know of so far.
I have however recently found out about these browser based games like Hobowars and have to say that I enjoy my time on these a bit more. I like games like this as well as Runescape but find it diffacult to stay with them. Runescape was just not really enough to do for me and once you had done it all it got boring. Hobowars is great. I have no complaints but I would like to find the next Hobowars and get in on the ground level.
I also wouldn't mind helping to create the next Hobowars. There is alot that could be done to make it alot better of a game. If you all don't know what Hobowars is you should check it out.
http://www.hobowars2.com/32599/