Yes. And there's a difference in encounter design and conversations.
4 members just allows Larian to get by with fewer companions.
I know they aren't going to budge on this but I would much rather they had spent their money on hiring additional writers instead of voice actors. The VO has been stellar - but I would happily trade those hours of VO for a handful of well written companions.
In BG2 and WotR if you don't like a companion that doesn't negatively impact the game. In WotR I'm never going to like Wenduag or Greybor. But that doesn't matter - if I don't like those two I have 12 other companions to choose from I can always assemble a party I enjoy playing with.