Hate truly is a strong word. Excessively strong for how readily people use it. A few weeks back I was driving some friends home from a house party. One of them kept using the word 'hate' to describe another guest at the party. Specifically, this person was saying that they hated the other guest, because of some perceived social faux pas this person had committed against them in the course of the event. I stopped my friend in the midst of their exaggerated ranting and said: "Hate is a very strong word. Usually if a person hates another, that means they would be willing to kill the other person."
My intention was to get them to stop being so flippant with the extreme language they were using over something that was ultimately, incredibly trivial.
Anyway, a bit of aside there. My point is I agree with you, specifically in the sense that people use the word hate far too flippantly and more generally in the way people overuse extreme-meaning words to the point that they actually lose all meaning. There's always more nuance to be expressed. Why don't people take the opportunity to do so? Like you say, disappointment could be expressed instead and in most cases this would be more honest, in my opinion.