My main issue is, that you don't encounter any interesting personality.
The issue is not that they're not from bg2. But what are the companion from past games compared to the mediocre companions now? We had a mercenary dark, grim dwarf, an annoying elf without wings, a crazy Ranger etc. They were all just normal personalities fitting into the world. Now we have someone like iron man, that is even playable.
They're are special because they're like superheroes and have such an over the top backgroundstory. I posted a thread about that even at the beginning of EA, and alot of fans agreed but Larian copies alot from divinity unfortunately.
Also that you know from the very beginning who can join your group before playing one second is imo such bad design.