It is EA. Optimisation is always one of the last thing to do, and especially a game with this complexity will need a lot of work to be efficient.
How good will it be when 1.0 hits? I don't know, on my old laptop Divinity: Original Sin2 was a rough experience until the Definite Edition hit (and the optimisation that Larian had to do, to make the game run on consoles).
As to "Why can I run game X and not this?" Even ignoring fact that BG3 is unfinished, there is the matter of how complex the game is. Didn't play Like a Dragon, but in Yakuza's most of "the world" is uninteractable window dressing. Same as Assassin's Creed game - a lot of visual flair, but not actually many things to keep track of. Hitman, however, has been always more demanding as it runs the simulation of every NPC in the world - for example on my laptop I did notice major FPS dips when I raised an alarm and NPCs were becoming more active. Where BG3 lies in this "visual flair or simulation" chart, I have no clue.
Still, if you are worrying about running the game, I would wait at least till 1.0 is released. At this time it is anyone's guess where will the game end up. Devs most likely have estimates and hopes only.
