Should the government publish intelligence gathering activity? Do you think there was no embellishment of English atrocities during the Revolutionary war or during our various other bouts throughout our history? Human nature is no different now than then.
Since time immemorial politicans have manipulated info to serve the needs, as they saw them, of the country. Sometimes they serve not the needs of the country but of the despot, that is true. But that is not the case with American politicians, they are elected and monitored.
You don't get to be a great nation by letting the population govern where they do not posess the proper information to do so, and where providing them with that information would compromise present or future states of national finance and/or security. AISI, it has never been part and parcel of successful governance, and it never will be.
First of all, I think that war is a unique event. The decision to go to war is unlike any other that a leader makes. If he lies in order to get the people to fund some new sewage treatment plant, I would still oppose it on ethical grounds....but its not a cosmic problem.
In war, on the other hand, you are asking people to kill and be killed. You are asking children to lose their fathers, wives to lose their husbands, and young men (and women, of course) to kill other human beings. Cities burn. Buildings are flattened. To ask people to do this while not being fully honest about your motives and goals is a moral atrocity. If the motives are pure, they will stand the light of public scrutiny...and Americans will step up and fight.
Furthermore, lying for a "greater good" quickly becomes a bad habit. The first lie may seem like it is for a great cause....maybe even the second one too....but eventually, the leader turns into a Clinton who lies morning, noon, and night over just about everything.
And yes, this sort of thing has happened for time immemorial. Unfortunately, the history of human governance is not a very pretty one. Those two facts are closely related.