I would just like to add another voice in the pro for the option of more companions. I think now would be the time to implement that so things can be rebalanced around it. It would then be even more of a challenge for the die hards that really like playing the game as a solo act, and people could still do 4 if they wanted, but having at least 5 would give more options in combat without having to try to make due without a rogue/mage/cleric. Or we could just have everyone be bards so all things are possible!
Reality is Merely and Illusion, Albeit a very persistant one - Albert Einstein