I highly doubt it has anything to do with DOS II.
4 is a very common party size, especially for Games which support Multiplayer and even more on Console.
That you can not have any utility in the group is exactly the point i think.
You have to make choices and this also adds more replayability to the game.
To me it doesnt matter if ots a 3, 4 oder 6 Party, but blaming DOS again is just random., i think there are good reasons for a 4- party