This is great debate. To save time, I am going to lump everyone's comments int a general statement:
If you create a new server, make sure it keeps the players interests.
I think both DMing and scripting are useful in this regard. But I want to add a third method, and that is game mechanics.
You can never replace DMing, it is the core reason this game stands heads and tails above the rest. I have always liked the DM's RPing as deities, and by doing this it gives the DM's a goal to strive for as well. Perhaps there are two or three main factions, each has favor of a particular god. Each runs quests to keep their side on top. You could even try to o this in a war, though that is a bit more tricky. Obviously, this would allow ebb and flow, with possibly some awesome dramatic moments and plot twists. Now I know this is a tricky bit to pull off, and I can see some clear pitfalls, but I think if you have a checks and balance system it could work.
Scripting entails everything from quests/conversations, puzzles (I REAAAAALLLLY love these), haks, dynamic weather systems, HCR, crafting, housing, death,and loot systems... and probably more. I think all of these can benefit the server. Unfortunately with resource limits, sometimes we may be forced to choose between some of the lesser ones. I guess the big takeaway here is make sure you got as many as you can get, because there is ALWAYS something that can be worked on. On a side note, I am not a scripter myself, tho I can talk in algorithmic pseudo-code some times. If I do continue into this adventure, I will be needing a good scripter (or 5 ) to help out.
I think the real core items here under scripting are conversations/quests and crafting. These two things are important in keeping players busy while DM's try to fight demons and monsters in their real world workplace (bosses, and if your work is like mine .. *sigh*... mini-bosses). I agree with everyone here, that good storylines here can help. Personally, I am a bit more of a goof, so I would probably inject a lot of geek references and humor into my quests, just because its who I am. Don't worry, I will have some very serious parts as well. I think I will save the storyline part for another post if it is needed, and go into details on those ideas then.
The last one of the three was game mechanics, and you are probably saying, well, you covered those under scripting. Well, partially, but what I feel alot of servers lack, and understandably so, as it is a nightmare to understand, is the balance between players and creatures. There are many layers here, and I will start with the 900 lb gorilla in the room. Class balance, and yes I have personally witnessed way too many servers die from trying to properly nerf spells or play around with HIPS until it is useless. The issue I have always seen is usually when two player PvP, and someone kills another person. So to try to minimize this issue, I would most likely outlaw PvP and evil chars all together to start out. As time goes on and players join, maybe a major campaign would introduce some of these, but personally, I feel that the DM's should provide the evil in the world, as this allows better checks and balances. That all being said, I think mage spells are weak and cap early, so I would boost spells up to match damage provided by fighters, in conjunction with that I would probably eliminate potions of healing to make clerics more useful (may also get these through potion brewing). I would not allow ANY items with direct immunities. I may allow +15 (number just for reference, i have no clue at this time what this would be, to ensure balance) to particular rolls or skills, but never all out immunity. I think those unbalance the game needlessly. Coupling these with a highly dynamic random loot generator, we can have the high players always searching for the right item. This will add some boss and zone replay-ability as well.
So to end this post, I guess the first thing I would do, before I started building quests and areas and funs scripts, is get my game mechanics where I want it, especially for PvE. That is key for me. I would rather take a year play testing and making that work, instead of focusing on the other items. Crafting is a system that can be added, as well as most scripts and areas. What you cannot do, is change the core game mechanics after launch, without affecting players in a negative way (usually negative).
Well I rambled long enough, I appreciate any comments and feedback, after all, I am using this to help me align my own thoughts and I want to come up with a good system that works for everyone. Just like all of you, I want to bring NWN back, to be better than ever.