Hmm, most things sound like my own wishes for D:OS. I have played the Cyseal part of the game in Classic Version about 10 times, every time I finished it I started again and again, absolutely addicted to the game world, the characters of Cyseal (Esmeralda and Septimus, Sam and Maxine (one would expect a romantic cat love, apart from all the weaknesses of human character, but actually it's an ironic analogy to the world of mankind, haha, not a romantic projection of human wishes), and all the other characters), the innovative combat system, the dialogs and their humour (ironic, delightful, not trying and failing to be dark, 'mature' or serious - a good complemantary part to the main story), the bosses (the Lighthouse Horror, the Skeleton King and his rawboned Lady, and the Dingdong-Dingdong-Dingelingeling which, unfortunately, got a very bad voice in EE, Braccus Rex whose crystals now don't make the fight harder, just tedious) and the absolute motivating looting in this part of game which was also changed for EE, and, I think, not to its best: the brown/orange legendaries don't drop with these well-chosen chances any more (not 100%, but not frustrating low, so evoking enough disappointment to be eager for the next boss fight), the stats have been changed, so many legendary drops don't feel legendary at all, and the uniqueness of legendaries got replaced by even more 'unique' types of items which feels just like 'too much'). The Cysealean part of the game was the most surprising and satisfying game experience since Gothic I and II for me; it shows, as you said, how much potential this game has and how skilled the developers of Larian Studios are.
Unfortunately the EE added more content to D:OS but didn't really sustain or expand its strengths (for whatever reasons...).
I'm sure there will be some more improvements from mods and I don't have a problem with the Editor, related to its accessibility; the GM mode will be a more handy and playful tool for those who don't want or are not able to get into the Editor due to a lack of time or knowledge, I think. And those who are serious with modding will get into it. The main problems I have with the current Editor is its limitation of modding fundamental things like attributes, abilities, talents, traits; it subtracts a lot from this powerful tool, not speaking of its general non-polished state (probably never meant to be due to other priorities or 'interests'): crashing, things not working as they should or being much more inconvenient than necessary, unfinished, and left alone in that state. Therefore it feels a bit like Larian Studios not caring, and, indeed, in the main they care about D:OS 2: it's absolute understandable. They have achieved a good basis to create a game they never had the chance to create. I guess they're trying to put everything into the game they have, even their souls, if necessary. - But I agree: D:OS could get (much) better (especially many parts after Cyseal) and much more more weight if they supported it 'right'.
Sometime before i'm dead, i'd also be happy seeing someone doing 'Divinity Original Sin: The night & day Edition, Now with Schedules'
Day and night would be really awesome but regarding the design of D:OS I imagine a Day and Night cycle would be a good one if it wasn't a [b]cycle[b/], independend from the story. I mean: I have never read a book with Day and Night cycle, where the sun rises and goes down and rises and goes down regularly. The sun just goes up and down when the story says it to go up or down.
