Richard G Davis, who was (may still be) the official historian of the USAF, says that the USAAF deliberately changed the "city area" category to "marshalling yard" as a means of claiming they weren't area bombing, but continued to carry out area attacks anyway.
That's a common strategy when the policy becomes unpalatable -- sanitize.
The other strategies I've heard to gloss over such things would be censorship (after all if you can legally make it illegal to publish, it usually cancels out the truth long enough that anybody who was involved would be dead or dying), and officially end a practice/program while creating a new one that does the exact same thing (an example would be the Phoenix program, it was ended in 1971, and a new program was called F-6 in its place).
"The AAF never officially acknowledged that it had bombed German city areas as a matter of policy. Analysis of the Eighth's bombardment policy, of its employment of incendiary bombs, and of its targeting of "city areas" and "marshaling yards" clearly reveals that, despite denials, it did engage in the deliberate bombing of German population centers."
Well, saying
"We'll be carrying out a systematic policy of killing civilians by bombing and setting fire to the towns and cities they live in under the presumption that, if we create enough pain, suffering, and death, they'll do anything to make it stop" tends to be viewed kind of negatively...
The Americans wanted to dissociate themselves from the British effort
I think it's more than that -- generally, the idea is to paint the enemy as completely and totally evil, and to paint your side as totally good, or at least reasonable and fair.
When your side does something that would be viewed as objectionable, the goal usually is to cover it up, as many fear that it would cause a damaging debate that could either be harmful to the nation, or at least reduce the popularity of the war (this is more likely in this case).
When Eisenhower told Spaatz to prepare plans for 'Thunderclap' the latter protested that it would compromise American claims regarding "precision" targeting of military objectives. Eisenhower replied that while he too had always insisted that "US Strategic Air Forces be directed against precision targets" (he had not), he was prepared to try anything that "gives real promise of ending the war quickly." This was to be an attack on the morale of the people of Berlin. Spaatz instructed Doolittle to be ready to bomb Berlin "indiscriminately". Maybe because 'Thunderclap' had originated with Portal and the British Spaatz also protested to Arnold, "There is no doubt in my mind that the RAF want very much to have the US tarred with the morale bombing aftermath which we feel will be terrific." He either wrote that with an eye to posterity, or in an act of self delusion.
Eye to posterity: The original plan for Thunderclap called for using the USAAF to wreck around 2-3 square miles of city with 5,000 tons of ordinance with a day-raid, followed by a night-raid by bomber-command (I would not be surprised if sector bombing would be used for this, as it had been employed in Darmstadt a month earlier).
As a rule of thumb the USAAF had little compunction with bombing civilians, they just were deathly afraid of looking bad doing it, and the effect that this would have on their "legacy" -- maybe they thought it'd prevent their wet dream of gaining an independent service. There was only one General, Charles Cabell, who seemed to express any real issue about the morality of such bombings, though there was an image based concern that it would leave a blot on the USAAF, he also seemed to feel that the raids were "baby-killing schemes" that were aimed more at "retaliation and intimidation for the future", than simply ending wars rapidly, and that he had doubts that world peace could come about by killing more women and children (all in caps are basically his exact words, the source of these quotes were from "Wings of Judgement").
I'm not sure about "retaliation", as it seemed that all independent and wannabe independent air-arms wanted to not just bomb cities, but launch first strikes (first attack the airfields, then bomb, burn, and gas the population). Intimidation for the future does sound about right -- General Frederick L. Anderson even basically said that he didn't think Operation Clarion would end the war any faster, but that having thousands of bombers and fighters striking Germany all over would be passed down from father to son, and prove a firm deterrent from waging war again.
Le May finally dropped all pretence with the low level, night time, incendiary raids on Japanese cities, but that was bombing Asian people. In Europe the pretence was maintained, and many still believe it today.
We viewed the Germans as humans that went bad; many viewed the Japanese as subhuman (General Hansell actually said more or less that he thought there was some sort of unwritten rule that the Japanese were viewed as subhuman -- I admire his candor actually, though I don't think it's right to view people as subhuman).
As much as everyone chortles at Stanley Baldwin's (and Douhet's) expense, they were -- and are -- 100% correct. With regard to the one line anyway.
As I've said before, it's gotta be one of the most misunderstood quotations in aviation. He didn't mean that every bomber that takes off will make it through the enemy's air defences unscathed -- he meant that no matter what a government does with regard to defence, it wont be able to prevent its citizens from being bombed.
If that's correct, then you're right. More bombers actually were blipped-out on their way
out of enemy territory than on their way
in.
That said ... he, like most others at the time, might have overestimated the effects of that bombing.
Though as I've also mentioned, we luckily never got the full test. Things might have gone differently if everyone's cities were also contaminated with phosgene, mustard, etc. for weeks/months on end in addition to being blown apart and burned (as pre-war theorists had every reason to suspect was a possibility).
The death tolls would probably have been greatly higher (I have no idea by how much, but phosgene is remarkably deadly and, from what I remember, the amount needed to kill is below the amount one can smell) and damage to the cities would likely have also been worse because the fires would have spread more (you can't put out fires if you're dead).
I'm frankly amazed that nobody did employ poison gas during the war, though I'm kind of relieved about the matter.