I personally always thought an interface shouldn't really make a game. If a game is too "easy", it's not the single cursor interface what makes it easy, but more the puzzles in the game. KQ7 was easy, but I don't think that had to do with the actual interface, but with the level of difficulty of the game.
I've played some really hard games that are single cursor. That difficulty comes from the puzzles and the puzzles challenges.
If anything, multiple cursors give you variety of "narrations". But when most games do away with the narrations these days, there's no need for them.