I do not believe they've run out of surprises.
The Unexpected always comes at the most awkward times.
Anything beats an expensive stack of paper.
Anything you don't understand is dangerous until you do understand it.
I'd repair our education system or replace it with something that works.
The reader has certain rights. He bought your story. Think of this as an implicit contract. He's entitled to be entertained, instructed, amused; maybe all three. If he quits in the middle, or puts the book down feeling his time has been wasted, you're in violation.