In my opinion Forgotten Realms has never been a very dark medieval setting apart from specific places. It had loads of very exotic places, races, events all over the place. Also the general high fantasy setting does not fit to a more gritty or realistic medieval setting.
If you want a more gritty medieval setting with central and eastern European influences only Ravenloft really works for D&D and else you only get it outside of D&D.
I think peoples mainly get the impression from the more pastel colors out of the graphic style used in the old engine. I am playing RPGs and niche games plus P&P for 30 years and would not have a problem if modern fantasy would still be 1980s Sword and Sorcery and have aesthetics like the Conan Movie or D&D source books back then. Its just not realistic to expect that and new stuff still can be good. I have seen the same complaints happen about 3D graphics for decades that it looks too vibrant and comic like.
Not every game can be Kingdome Come: Deliverance. Also its honestly more fitting for Forgotten Realms to not look like Ravenloft. And hopefully we get some graphics options or modding/post filters from peoples who really need a darker palette you can use external tools for that.
Its a duverse setting, with adult elements in plenty, but as a whole, thr Forgotten Realms is a hopeful uobeat place for a world that keeps gettimg hit by aovolypes and then repaired.
