I don't think people realize what it would mean making 20+ companions in a game like BG3.
Fully animated, voiced companions. With quests. Different outcomes.
Compared to a one voiced line at the start of each text conversation, no animation, no quest (a few of them had one), no way of influencing them.
I still prefer what we have now.
I think 10/11 is a decent number of companions, the problem is the way Larian implemented them. Over half are stupid evil and unavailable to the vast majority of playthroughs, two are cameos only available halfway through the campaign. That leaves a single party of four characters 3 evil with redemption arcs, one neutral.
The way it should have been is either have a larger number of less involved characters or make the characters more flexible. If you have 10 characters each of which will fit with a few classes and can all be at least neutral aligned that gives a lot more flexibility for building a party.