hmm, my two-cents (I don't claim any of these are a problem here, nor am I predicting them as likely, just espousing thoughts)
-A dynamic world, not one where established authorities/institutions are so heavily locked in that nothing a PC does will ever meaningfully shake them, or a PC group can never compete with them. And actions such as a Razing a temple, or similar effects shoudl be a long-term, not next-reset away it goes. (Allowing for time to alter the area/update the mod, of course). Obviously a DM supervion is required to this, but if that's there, the action should definately have a legitimate impact on things.
-Players and DMs having some sense of equality/fellowship/peacefulness outside of the game. Neither side should really consider itself a side, as if it were a combative war. This is of course has to be done by politeness on both ends. Largely this point's already covered, so I'll leave it. Ingame, a DM's ruling stands, on out-of-game matters, arbitrary authority just leaves a sense of elitism.
-A unique flavor. Alot of servers fail in this, rapidly falling into cliche plots (Oh-em-gee, Orcs are invading, how original), or aping other servers. Simultaing a successful place can be done with going overboard. If you make it near-identical, you may attract some players, but they'll always favor the original. That said, there are times when cliche is welcomed, but continous forcing of a set cliche is usually a bad thing. (EG all drow are always evil, all the time. Sure, you don't want Drizzt running around, but there's a Major Deity for Good/neutral ones, so they obviously exist, in significant percentages)
-Realism and rule-lawyering. Realism is never really a reason to implement anything. It's a fantasy world, beyond a basic level, realism doesn't apply. Rules-lawyering is another bad jsutification for changes, NWN isn't PnP, evne PnP arguably isn't balanced for any kind of PW activity, so if you draw up all the rules from a book for PNP, you end u pwith a flawed NWN PW.
That's all Ican think of at the moment.