If someone does overhype something it can feel a good thing is bad because it was not on par with his expectations.
The end product is what matters indeed, but one can look it in an unfair manner if it was expecting a lot more.
Good point I have seen people do this. Assuming one bases their opinions on the game itself, then their expectations shouldn't matter.
A game that it's good will not have the same impact if you thought it was going to be bad, or excellent. The surprise always influences your opinion.
Wait whut, how can your opinion be influenced by surprise if your opinion is what you're surprised by? xD
Expectations can be tied to preferences.
One person can expect a fighting game to launch with a certain mode, because they feel it's essential to the game. While another person doesn't think that mode is essential to a fighting game, and has no particular expectations on whether or not that mode will be included.
The first person becomes disappointed in the game because they feel it is missing something essential, while the second person is content with what they got.
I guess they can be but not always. You can prefer one thing and still expect the opposite i.e. I'd prefer good Pokemon games but I only expect more bad ones lulz.
In your example I'd say they don't matter. Even if that first person didn't expect it to be there they still wouldn't be happy it's not there. Like I said, bad thing is bad even if you expect it.