I purchased D:OS2 solely for GM Mode because as an avid D&D GM I was excited about the prospect of having such a strong, versatile visual medium to play a tabletop-like game. I had a long-ish running D&D actual play podcast that ended abruptly, so my plan was to turn it into a Twitch stream using D:OS2. After one session/stream, my players were unable to join the session due to a bug and we didn't play or stream.
Two weeks later, the bug has been fixed, yet I still had to jump through hoop after hoop to make the game work. Twice during that session, while live on Twitch, our game crashed unexpectedly. Not only is this frustrating, but it is really embarrassing when you're playing live for an audience. The crashes were a result of mods made in Divinity Engine 2.
My longwinded point here is that after so much excitement and enthusiasm, the repeated issues with trying to run GM Mode have completely turned me off to the game as a whole. For 6 weeks after launch, I spent 5-6 hours a night working in the editor, preparing my campaign, and organizing my stream. For two weeks now, I haven't opened the game once. To answer the original question: yes, GM Mode needs to be saved. As it stands, for me to run an effective campaign the way I envisioned requires far too much troubleshooting and bouts of frustration. Until significant improvements are made to this mode, I am just unwilling to put any more effort into it.
And yes, I know that any time you mod a game you run the risk of problems. My frustration stems from the repeated mentions from Larian during pre-launch promotion that Game Masters can create their own mods to tune GM Mode to their liking, and then finding that mods (btw I'm only using 2-3 at the most; almost entirely cosmetic at that) cause continuous issues, errors, and crashes until I just don't want to deal with it anymore.
Yes. Please save GM Mode.