Hm.. I think you should have rewards for completing all side quests / puzzles and mini games. For example, I don't complete chapter 6 "the forbidden one" quest because it took me lots of money and even a greater ball, and the reward is.. useless imo. However, if complete all side quests will give a nice reward I would think again about that... Further more, it tooks lots of time to complete all puzzles / mini games, like car racing mini game for example, we should be rewarded