2_ no branching dialogue or deep dungeon customization
3) the overall dm tools were weak - People wanted deep dm control
2) To clarify - SCL (Sword Coast Legends) had only "random" dungeon creation. "Authors" want to be able to "set dress" and create their own story, their own dungeon layout, their own lighting and sound ambiance.
3) I think the "DM" tools - the "live" DMing tools were pretty good and allowed DMs to interact with their players. The "Author" or environment/scene creation tools were the major issue/failure of SCL. (Many) Authors want to be able to create their adventure and NOT have to interact and have their adventure be able to stand on it's own and not require a DM. Likewise, there are many solo players (and small groups) that don't want a DM overseer and simply want to play a good story. They might even have limited time-frames due to real-life constraints so they might only be able to play a few minutes here, a half-hour there. They need to be able to pause/save their current status and continue another time.
SCL had a few nice features for the DM...
a) a "wisp" that could be turned on/off that the players could see -- allowing a DM to "guide" players to an area if needed.
b) Taking "control" of any monster/npc and using that creatures abilities.
c) Adding/deleting "set dressing" on the fly -- scenery objects - boulders, trees, tables, dripping water, etc.
So, in my opinion, the essentials for D:OS2 can be summarized as...
1. Take the "authoring" environent/creation/dialog tools of Neverwinter Online
2. Take the interactive "DM" tools of SCL.
3. Take the scriptability of Neverwinter Nights