I think I disagree what original BGs were - I didn't think the original trailer fit BG IP at all.
That said I do agree with the sentiment. D:OS1 was silly fun all throughout - nonsensical plot, characters who were more about puns then anything else, riddiculus combat. Audience wanted something more "dark" and "mature", so Larian obliged. D:OS2 was a silly fun with a lot of macabre and dark twisted stuff. I didn't like it.
BG3 seems even darker, but silly Larian DNA is still underneath. I am also not a fan of what Larian considers "mature" content - from liberal cursing, to explicite sex scenes, to some really "yuck" moments. I think Tarantino comparison is very apt, with the difference that Tarantino understands very well camp, and explotation. I am not exactly sure if Larian's humor flyes over my head, or if it is them who don't get it.