DM Mode and the Toolset should not be confused, as I think they are in the above discussion. DM Tools are for taking over the story and "taking off the rails" of its design so that the players experience the unexpected. Being able to edit dialog trees strays into the toolsets domain and I think really isn't needed.
If people interested in this game want to help, they really should look at NWN or NWN2 for the best (even to this date) examples of how it's done. While NWO and SCL offer a modern way of doing UGC, both fall very flat when compared to NWN 1&2 in terms of toolsets.
This game is offering two very different features: 1) DM Mode which allows a player to take over a story and drive it in new directions, and 2) A Toolset which allows players to author custom stories & game spaces, and modify the main game.
The two should not be confused with each other. They are two different goals on Larian's timeline.