The only turn off I have about BG3 is the level cap.
This is due to the fact I already play table top a lot and am sick to my back teeth of levels 1-14. I have seen high levels in table top only a handful of times, due to various reasons.
Those times where I've gotten to a high level have been the most fun I've had in D&D with the least amount of drama among the players cause we were all badass and were powerful enough for the DM's to go to town on the story throwing what ever he wanted in. From Barbarian invasions to terrask egg babysitting (long story) it was amazing.
I was hoping BG3 would be my opportunity to have an adventure in D&D that allowed me to play how I wanted, to a high level...
If we don't get 20, so be it, but I am hoping we at least get to 20 at some point via a DLC if it is not there at launch.
That all said, every one enjoys the game differently and I aml just glad to have a D&D game with the 5e ruleset.