You can also check out sites such as Game Rankings to get an overview of how magazines in English speaking nations reviewed Runescape, whether they liked it or not, and why. I'm not suggesting you do a raw data poll of these sites and go by the results, but it should explain why some people enjoy the game.
Bear in mind, MMORPGs have some of the most inexplicably loyal followings. Usually because the people who play, and get a sense of community from other live players, project this sense onto the game code, where it doesn't exist.
