Invincibility give a lot of unique charm to the game, even if it resulting in punishing by making you redo certain sections sometimes, it gives a pretty cool seamless feeling. And also encourages for you to experiment with everything without fear...
Hardmode Zeekeeper nearly filtered me from my M&L marathon... but I beat it. The saga continues!! Thank goodness there are no more annoying battles that rely on the ever delicate touch screen and gyroscope in that game.