This is according the game’s lead designer, Kevin Martens and art director, Christian Lichtner during an interview with Rock Paper Shotgun. According to Martens, one of the reasons they made the game have an always-on requirement was so that gamers could play with each other. He cited an example in Diablo 2 where offline characters and multiplayer characters were separate, so if a gamer wanted to hop into a game with friends, he/she would have to start all over. “The game is most fun when you can play with other people. To be ghetto-ed off to the side and not part of the real game, we didn’t want that to happen.”
There you go, straight from the horse's mouth.
BE HE TRUTHFUL?!