Party of 4 - can't have ANY origin characters in the party if you play 4 player multiplayer.
Party of 4 - monsters need nerfing and don't have proper stats and behaviors.
Party of 4 - you don't get as many dialogues as you adventure.
Party of 4 - you have to constantly switch out party members just to do basic side quests related to certain characters.
Party of 4 - characters sit at camp "idling away the hours" when they have tadpoles in their heads and should be helping you not die against tough enemies like the Gith patrol.
Party of 4 - the grove is getting attacked and everyone is going to die, but characters like Wyll don't participate because you left him at camp. Guess he really didn't care that much after all, eh?
Come on. Party of 4 makes no flipping sense in the game. The only time I'd actually ONLY travel with 4 is if I was on a stealth mission. If I have 6 party members at camp, I'm gonna take all 6 to face potentially difficult situations like having to defend a grove against a goblin horde led by a bloodthirsty Drow cleric lady... Or if I'm going to waltz into and raid a goblin camp and kill their 3 supposedly big bad leaders and then face 30 minions as I'm trying to escape.
