The point of playing is to play, complete the game, understand its meaning and main idea, and immerse yourself in the game. But the moments in the game that a person simply cannot overcome end up pushing them away from the game as a whole; it becomes tedious (if you have to replay the same mission 10 times, it quickly gets boring).
For example, Heroes 5 is a very interesting game with excellent graphics, but in some places it is so difficult that you have to spend a huge amount of time and energy to complete it. I'd rather add a couple of hundred units to my army and crush the guy who's preventing me from progressing and learning the rest of the story than just stubbornly banging my head against the same obstacle.
I completed all the previous Heroes games without cheats, but in none of them was it as difficult (except for 3.5 - that one was a mutant, and it's not even worth talking about).