This question makes me think of the idea of "attachment to illusions" in some Eastern philosophies. Basically, when you set an expectation, the mind becomes "attached" to that idea and wants reality to conform to the idea.
Sadly (in my case at least), reality rarely is what I want it to be. Thankfully, it's often much better than I could have imagined. Because of this, I think that having ANY expectation is a bad thing, regardless of how high or low it is.
However... It is human to have ideals and expectations. It is the path of wisdom that allows us the opportunities to accept the world for what it is and let go of our expectations. Once we make peace with reality, moving through it becomes much easier.