And yes, of course you are supposed to seek out the parts of the game that are actually challenging. Whether your content with that or not is your own personal problem. But complaining about how the parts of the game you want to play don't fit your definition of challenge is the defintion of being self-centered. Technically, Blizzard has zero accountability to the player base. They can do whatever the hell they want. They certainly have zero accountability to you.
Don't hold your breath waiting for Blizzard to create a game that perfectly fits what you want because it's never going to happen. If you don't enjoy the game for what it is, stop paying and move on. I fail to see how complaining about how it doesn't fit your narrow standards is a productive use of time.