Gazoinks: Not too complex, then? (As in friendliness, not what you can do with it)
It's surprisingly similar to the Morrowind editor, which is the only other one used extensively. Build with tiles, lots of "if this then that" scripting. With only two wiki pages and an hour you can make a small dungeon with a kill 'em all mission. Works well.
I would guess it will be simple to make a module that is basically a series of shadowruns, which is what the "official campaign" basically is. Making a real open world CRPG would be a lot harder, which I am guessing is why they didn't do it yet. It could be done though, with the engine and tools, for sure.
Crosmando: I haven't been able to work up the will to finish Dead Man's Switch yet. I don't mind linear if the hubs are freely explorable and have side-quests, but this takes linear to a whole new level.
I got over the disappointment when I stopped thinking with my RPG brain and took the game as a strategy mission-based affair. If you think XCOM or even Syndicate it makes a lot more sense and is of high quality for that kind of game.