Why Don't MMOs Allow Easier Transportation?

Rock, Paper, Shotgun is running an opinion piece which asks why the majority of MMOs force users to spend a fair portion of their time traveling around a virtual world. At what point does moving from one location to another become a chore? From the article:
"I love big, explorable worlds. They're by far one of my most favourite things about games. Running off in a direction without any idea what I might encounter is a rare pleasure, and one far more likely to result in an exciting discovery in a game's world than the real one. ... Not knowing what's coming up is huge and exciting, and I'd not want to take it away from gaming, not ever. But you know what? Once I've been there, that moment's gone. I've discovered it already. I did the exploring. I don't need to spend half an hour of my time that I've allocated for playing games trudging at whatever stupidly slow speed a game's decided to impose upon me. There is no good reason, whatsoever, to not just let me be there."

http://games.slashdot.org/story/09/0...Transportation