I agree with Sanji. It's not really that hard to make a character with infinite health during a campaign mode and temporarily increase the difficulty, the fight will last until you die and the story will progress like it did. It won't even be frustrating and you will move on. If it was a Fighting Game, that same theory could apply, but anything outside of story obviously they all would have to be equal (except if they are really low-tier).
However, I still enjoyed every bit of it but I am just defending the argument that it will enhance the expirience.
You pretty much remind me of a great star wars game called Jedi knight outcast. Obviously, you end up using a lightsaber and feeling as awesome as a Jedi. However, you only get to be a jedi at around 1/4 into story because during the first quarter you are just a regular human being in a typical fps game (its incredibely frustating cause I HATE fps). As a normal person, you eventually end up meeting the final boss early in the game but he literally toys with you (choke force, force push, lightning, deflects your blaster shots), taunts you and "kills" your girlfriend (which forces Katarn to become a jedi again). Its frustating to be normal but you get to see how fearful the users of the force are and builds up expectation for the final duel. Later, The moment when you meet Luke and obtain your lightsaber and force powers are incredibely satisfying moments. It is an absolutewhen you start kicking butt as a Jedi in a story that is faithful to the original trilogy.