I'm going to go out on a limb here (and probably make some enemies):
I think the thing that has really upset Jazz fans is the simple fact that Hayward left the Jazz for "greener pastures." All the outrage over the method of the decision, the delay, the lack of pressing for a sign-and trade, the supposed lies, the apparent lack of letting the Jazz brass know in an honorable way, etc., etc., are excuses we use to mask our discomfort with a decision that we know he had a right to make. Those other things reflect poorly on Hayward, but likely say much more of immaturity and poor planning in an unfamiliar situation than true moral shortcomings.
But the discomfort we feel with Hayward's decision is real and biting. To put it in terms that ijazz can perhaps understand, it's as if Hayward decided to leave Butler for Indiana University after Butler's finals loss, saying how much he respects IU's coach and would be better able to fulfill his dreams at IU.
I understand completely why players generally (including Hayward, and likely many more of the current Jazzmen than we'd like to recognize) are willing to move for what they regard as a better situation. I don't resent them for that. But those decisions (especially when the movement seems to be from the "small time" to the "big time" and not for overwhelming basketball or financial reasons) leave fans with a pain that there is no good cure for. I'm not into the lifetime grudges that many Jazz fans seem to hold, but I understand them.