I never really considered Luke as holding them in a high regard. He didn't seem to know much about them at all. I'd think the average citizen probably didn't care too much. I'm sure the vast majority of citizens had never seen one and knew minimal about them. It was the senate and Republic politicians that interacted with them most, and when Palpatine, the leader that saw the Republic through its biggest crisis stands before the Senate and accuses the Jedi of treason, they Senate probably has no reason to doubt it. There is also a cut scene in which Mon Mothma explains that the Republic senate knows where the real power is (Palpatine) and that they would do whatever it takes to share in it. So when Palpatine declares the Jedi to be traitors, many senators might have supported Palpatine just for the sake of getting on Palpatine's good side and hoping that it would result in political alliances. More than that though, and I've brought this up in the TV forums, I would wonder if Palpatine ever revealed Anakin's role in Order 66 and in protecting Palpatine from Mace. It would probably go a long way toward convincing the Senate that the Jedi are traitors, if he can convince the Senate that there was one Jedi that refused to go along with the alleged treason plot and chose to remain "loyal" to the Republic.