I'm gonna chime in and say that first that yeah, if I had to pick I would like BG3 to be as loyal as Solasta because I quire like the 5e system when translated into a video game.
That being said, I think the issue is deeper than that. I personally am not married to 5e as a system and can take it or leave it for the most part, it's far from my favorite system. More than anything, I think that the changes that Larian has made just...don't really work great. They feel clunky and off and counter-intuitive at times. That's not because 5e can't be changed at all without breaking it, but because the changes that have been made aren't really compatible with the system.
To give you another example, there was a game called Torment: Tides of Numemenra, released several years ago. That was based on something called the Cypher system. I love that system and I love the game, even though the game had to make changes to the system, since it was a more story-focused system that doesn't translate well to a rigid video game. The changes worked there because they felt natural and the rest of the mechanics around those changes mixed well with it. On the other hand, BG3's changes feel like they were added in without a lot of thought for how they're going to interact with other mechanics. Which isn't great.
So while my personal vote would be to make the mechanics more loyal to 5e, ultimately I care more that they just pick a single lane, rather than this half-baked product we have.