The simple fact of games these days - Every Non-MMO but still Multiplayer game should have the option of 4, 6, or 8 players. Or more, depending on the type of game. But a game like this where you are bulding a party to play it should ALWAYS have the ability to add more RPCs dpending on the group of people that want to play together. My game group has 6 people in it, and we have to leave people out because of the stipidty of a 4 player system. NO GAME SHOULD HAVE ONLY 4 PLAYERS MAX. If the problem is connection speeds or resources for the game itself, then that should be on the user to make it right. If the problem is ease of completion, then it should be on the devloper to scale the difficulty to the number of RPCs. Limit the NPC slot list if you want, but the players should have a choice as to how many can play at a time.
It's that simple.
I don't care if the studio has a history of 4 player games.
I don't care if people are crying about length of battles or interations because of a larger party.
The number of people playing should be player controlled. Period.
I wish developers would get out of the past and realize this. There is no logical reason for only having a 4 player multiplayer game anymore.

Just my 2 cents