I don't have the time nor the desire to replay the game on different difficulties. (blog.us.playstation.com)
But your point is a good one — I don't know if I'd have the patience to replay games in order to gain «mastery» of them. (gameological.com)
The amount of times you die can be viewed on the bottom screen of the 3DS version, to encourage you to replay the game with fewer deaths. (wiiloveit.com)