>>21923282It's probably a lot of work to balance and test the game for more difficulty settings. They usually fuck up enough with even one setting.
Also, and this is just speculation, maybe they don't want to make the players insecure by giving them a difficulty choice right at the start of the game?
Sure, most players are old enough to undertand a difficulty setting, but they still deal with a lot of kids and they can be pretty retarded.