You can't make everyone happy. A game is either for real gamers, or it isn't. A game has to be decided from the beginning whether it will be challenging or not, because a good game is entirely based around its challenge.

Adding a "hard" mode that has the same level design, but now the enemies take more hits or something, would be lame.

"Perhaps one did not want to be loved so much as to be understood."
-Orwell