Every game I've played with multiple protagonists... I've simply lost interest in playing them. Maybe it's just me being pretty narrow minded with stories but when I pick up a game I only want to be one character, as I feel I'm taking that character from A to B.
A and B can be physical locations, reputations, character development. I coped with the DLC because I treat them as seperate games within the same universe, but if they tried to hoy all three games into one game I would have lost interest by the second island.