I think randomness is mostly used to hide the flaws in an imperfect game. In a sufficiently complex game, the natural cause-effects from play should result in n

I think randomness is mostly used to hide the flaws in an imperfect game. In a sufficiently complex game, the natural cause-effects from play should result in new and interesting game states. The opponents inputs + the game rules should create something inherently exciting and intriguing. A poor set of rules can be made interesting by adding dice rolls. Creating an interesting game without randomness is much harder.