I think that could be explained easily. I don't like worlds which turn around the "hero" and his/her group and I don't like companions which are 100% to the main heros taste and licking his/her ... all the time. As allegedly the world is big and wild, there could be space for more parties of heros traveling around. The companions you see in the camp during rests do their own business the day over, they are just too polite to inform you how boring your adventures are in comparison to their own.
Except in BG3, there is nothing more important to our companions than our current main quest: deal with the tadpoles. Except for maybe Gale's bomb, but he tells us about that and requires we bring him items, and therefore isn't going off on his own to deal with it. So it doesn't really make sense that the companions aren't putting 100% of their effort into solving the tadpole issue.
I think it'd be interesting if, when you don't make quick enough progress in reaching each companion's preferred method of solving the tadpole (e.g., going to the Gith Creche for Lae'zel), the companions become dissatisfied with you. First they have a talk with you imploring and then demanding that you go there next. If you continue to do other things, however, they leave you to go there on their own. You'd be able to find them again when you go there, but perhaps things have played out differently than if you had gone there earlier.
Exactly. What doesn't make sense to me is that any of them are willing to sit at your camp and do nothing. They all have a vested interest in the main quest, and a few of them have a vested interest in side quests.
Lae'zel is the perfect example. She wants to get to the creche and she makes it quite plain constantly by nagging you that you aren't getting there fast enough. So why would she even allow me to tell her to sit at camp and wait there? It makes more sense to me that she would tell you where you could go and just how fast if you told her to sit at camp and do nothing.
Wyll is another perfect example. He pretty much hounds you right away, urging you to go to the goblin camp. So why would he be okay with you telling him to just sit at camp and do nothing?
Astarion is really hoping to find out more about the tadpoles so he can learn their secrets and control them. So why would he be okay with anyone telling him to sit at camp and do nothing when the best chance of finding out more secrets about the tadpoles is to go with you?
Gale has a bomb and he would be worried that you might withhold artifacts from him. So why would he want to sit at camp and do nothing? He'd want to make sure that if you find artifacts that he has to say in maybe acquiring them for himself.
Even Shadowheart expresses a desire to explore the area to see if she can find out more about the conflict between her people and her enemies, the Selunites.
So, to me, it really makes no sense that any of them would be okay with you telling them to sit at camp and do nothing. if anything, them being okay with it is more like them kissing your bum and just doing what they're told