Still lurking...
I saw it brought up in the design preview thread but it was never really answered. Does anyone know for sure, not speculation or "it makes sense, so of course..." or just guessing, but for sure, what the Quest Editor is for? The design preview mentions a forthcoming Public Release so it seems like it will be available to more than just TG employees to write quests for Horizons. But beyond that all it tells is that it will make quest creation better and faster.
Click.