An expectation works as a filter as much as a hope. Set one and everything that is not the specified outcome arrives already classified as a disappointment, including things that would otherwise have been good.
Ask people about the best day of a trip and it is almost never the day on the itinerary.
It is the wrong train, the museum that was closed, the café they ended up in because of the rain. None of that could have been planned for. It could only be left room for.