Now that it has been confirmed that we won't be locked into choosing a crew after act 1. There is no need for this stupid limit. We should be able to take up to 6 companions.
A six person party is certainly a popular request around these parts, and probably even a majority preference here, but I certainly wouldn't call a four person limit "stupid" as there are plenty of reasons folk, myself included, might prefer a core party of four. I'm sure they're all in this thread already so won't go over them again, but while others might not find them compelling it doesn't seem fair to dismiss them out of hand.
Of course, Larian could introduce some flexibility to enable larger parties for those who want it, but there is still the question of the intended party size around which the game is balanced, so it's not as simple as just saying that people who prefer a party of four could still play that way if the game supported parties of six.
(Personally, I have no objection to Larian enabling larger parties though it's not something I myself want. But I would prefer the game to continue to be balanced around a core party of four, supplemented with occasional guests for specific missions.)
You do realize that if they allowed for a 6 person party it would mean that the ones who prefer 4 also would get what they want? As it is now, only the ones who prefer 4 gets full enjoyment out of the game. That is why it's objectively stupid.
Game balance isn't free, far from it. The more you add party members the harder it is for Larian to balance the game. I really don't see them achieving to balance the game correctly for both 4 and 6 as they are already struggling with 4.