I've had something of a realization that some of the changes and alterations in BG3 (like the paladin) could be what WotC may be ultimately going for with their next iterations of the system. Meaning that a more or less purist 5e adaptation (Solasta) is actually not what they're keen on endorsing.
As for the Kingmaker difficulty remark, playing it on Normal makes it way too easy. Once you get past the pre-barony part, you're pretty much going to roll over everything except for perhaps Pitax and the Wild Hunt, maybe an optional boss or two. Once your characters can take one hit without dying and you have practically unlimited money and an ability to buy as many healing supplies and rations as you want, you are no longer in a desperate situation resource-wise the first act forces you to be in. They've pretty much repeated the BG issue where at levels 1-2 you are pathetically weak but become exponentially stronger later on, except BG is all low-level, so it still can succeed in kicking your ass on a regular basis (with enemy spellcasters), while in Kingmaker you can just keep interrupting Vordakai's spellcasting because they didn't think to have him come pre-Stoneskinned/Blurred/Mirror Imaged.