Just because I do normally pick 3 companions to run with for a playthrough, and stick with them, doesn't mean I want the others to die though.

It wouldn't even make sense in this setting.
If they just sit in camp, well that's how a lot of other games work. It seems that in the original BG games you had a ton of companions and could swap the party any way you wanted at any time. Just not all were equally well written as some.
I can handle companions going on their own separate quest/mission and meeting up at the end of the game, maybe.
I never played the Divinity series so I don't know how it works there, but I heard the other companions you didn't bring, all died. That SUCKS.