They already said they were going to add more companions and also we can hire mercenaries. So I don't think a variety combination is going to be a problem.
The problem is that every companion with a robust story is going to be an origin character that you can play at the start of the game and not meet along the way. So every origin character is going to have the tadpole in the head. So it means that every origin character is most likely a survivor from the mind flayer ship.
That into to game sounds too much like the DOS2 story.
That's also a part of the problem of course, I totally agree.
In the exemples I gave to talk only about the "numbers" criteria, all companions have a "robust story", are met along the way and have differents problems to solve.Numbers, quality AND variety
is important for companions.
You can't talk about one without talking about the others according to me because all these criterias are important for immersion, role play, choices... And that's what Baldur's Gate (and others) gave us.