Also, the lessons that I feel Owlcat could take from BG3 don't have anything to do with the parts of BG3 that are expensive (cool graphics, extensive voice acting, etc). (Plus said lessons could also be taken from Divinity: Original Sin I and II, which AFAIK are in the same budget ballpark as Wrath and Rogue Trader.)
IMO the biggest weakness of Owlcat compared to Larian is encounter design. Kingmaker and Wrath are full of bland, meaningless filler fights that are only really bearable because you can go through them quickly in real-time mode. Rogue Trader has similar problems, if not quite to the same extent - but there are definitely sequences in that game that have way too many fights against the same generic-ish enemies.
Meanwhile I don't think BG3 (or D:OS2 for that matter) has a single fight that felt like filler. That, plus the ability to use terrain creatively, does a lot to make the purely mechanical part of the gameplay much more interesting. (I just really ...