It would be nice to have 4+ characters in a party, I agree As mentioned somewhere by someone, I would love to mix a couple a custom-made characters with origin characters.
But I can understand if it doesn't become a thing. There could be technical and pragmatical issues. For instance, maybe it would be too difficult to "balance" combat encounters? Which is already not an easy job to do with PnP games.
I also don't think it's fair to say that Larian Studios is inconsiderate. They obviously listen to feedbacks given the different updates, they just don't have to obey every demands.