Star Wars Mud - SWmud
It is unfortunate that Daedroth was looking for a Role-playing environment, because we make sure to mention the fact that we are NOT one. RPing is accepted, but not enforced, and the general populace chooses not to RP most of the time, with some exceptions. Many players find this refreshing compared to the strict RP environments of other Star Wars based MUDs. You can't please everyone.
As for the quest issue: yes, a high price is paid for those who decide they cannot keep their mouths shut in either asking for secrets or repeating them. Though it may be human nature to discuss such things, it does not hurt for people to learn that sometimes your own discipline is required. If you want a guide explaining how to play a game, go to BestBuy or Wal-mart and buy a game for a PS2 or GameCube, and then go buy the guide that tells you how to play it. You won't feel anything near the sense of accomplishment you would had you figured it out on your own, without help.
As for rewriting quests: Yes, several have been rewritten over the years because of players (and sometimes wizards) who could not keep their mouths shut. However, as they are being re-written, they are also being modularized so that removing or changing aspects of it are/will be significantly easier in the future than it was for the previous version now removed. They will no longer require the downing of the entire quest. I have seen this in the quests that I've performed.
In the 7+ years I have played, I can remember 4 major quests being revamped, one of them twice (HM quest), and maybe a dozen secrets being adjusted to make them secret again. I also remember at least 9 planets being opened or redesigned (most of them very large areas - hundreds of rooms each), numerous smaller areas added to existing areas, and several quests. There was also the addition of the Jubilar TFC field, the Events system, major changes to the combat system and the economy, 5 new guilds, 7 new races, and a myriad of other minor fixes and additions, some player-requested and others not. It is not fair to say that the wizards spend all their time re-writing quests. The mud's website, http://www.swmud.org, keeps track of the major updates to happen on SWmud (http://www.swmud.org/mgmt/updates/). It is updated every 3 months.
Our MUD may be a bit more hack-n-slash than some would like, but there are other interesting things to do. There are many quests, but yes, they are meant to be kept secret. However, if you want RP, you will want to find an RP-enforced MUD; we are not one.
On the whole, SWmud is a well-built and well-run MUD. I do not call it perfect because we know we have certain issues to overcome (the biggest hurdle being the re-release of the HM quest), but it has kept my interest for over 7 years now. So, to each his own. May you find the MUD you are looking for, and may others find SWmud.