I don't think the 5E incorporation was "necessary", but it was a really nice format. They did a good job with it, actually better than Solasta.
I'd be curious to hear you expound on that a little more and explain your position there; what metrics are you using to form that opinion?
There is zero question that Solasta is a far superior implementation of the 5e ruleset as transposed to a video game, at least as far as combat and encounters (which do make up the greater meat of the ruleset implementation) are concerned - it's not nearly as pretty, of course... but that's a game engine issue entirely unrelated to the implementation of the ruleset.
Out of combat, BG3 is more dialogue, character and RP friendly,
absolutely no question there.