This is a tough conversation to have because there are no objective standards of quality when it comes to difficulty. What's easy for you might be impossible for me, and vice versa.
Now, I agree that it's unrealistic to demand an "easy" or "hard" mode from a developer, when that feature is not among its list of priorities. At the same time, I think it's totally fair for a consumer to cry foul if a game is pointlessly easy or painfully difficult -- to the point where it robs a game of its purpose and sense of fun. We evaluate games how we wish them to be, not how the developer intended them to be.