During my own DMing experience elsewhere, I remember how nice it was when I was new to the game. I was so patient and polite to the other DMs while they taught me, and took my duties very seriously.
After awhile, the faces that made up the playerbase started changing. I no longer saw the close friends I had made as a player, or even some of the people that I had loved to hate. All these 'new' people came, and it sucked.
Fewer and fewer players merited my attention or time. I stopped looking at the server as fun and considered it to be more like a job. After two years, I was no longer recognizable as the DM I once was. I spent my time wandering the empty areas of the world instead of interacting with players. There were other events involved that detered my love of the game, but the real reason I eventually walked away was because the playerbase and staff had changed around me, and I did not want to change to suit them but expected them to change to suit me. I detested them because their characters had it easier than ours, or I didn't like their RP, or just because I thought they were retarded. Dropping monsters on them as divine punishment for their imagined crimes was more rewarding than creating interesting storylines or providing exciting challenges.
I debated with people on the forums as well, to the point where I looked at nearly every post as a challenge to be overcome. Posts such as this were easier to look at as personal attacks on not only myself, but the few people on the server I actually associated with (my fellow DMs). I would simply get mad, quickly find ways to make that person wrong, and then ignore them entirely.
Perhaps I am a horrible person for assuming that the DMs on EfU aren't going to be 100% commited to each player throughout their course of their duty, or listen to every suggestion and criticism and consider it fairly, but I'm willing to say that, when put in a similar position, I was not 100% commited to everyone as I should have been, and I am assuming that another human being, in a similar situation, will share that experience.
The best advice I can offer DMs who start feeling like the game is a job rather than fun is to step away from the computer. Try staying off the server and forums for a week, or even a month. You will hopefully go outside, gain some perspective, come up with a fresh idea or two, and hit the server hard with much needed DM awesome upon your return!