It is intended as a satrical comment. The expected phrase would be "Oh, the inhumanity of it!" This expression would be used to express horror at some intolerable situation, i.e., the situation is inhumane. When someone instead says "Oh, the humanity of it," it is usually a response to someone having called attention to a situation that they find intolerable, but which the speaker believes to be perfectly normal and acceptable, i.e., that the situation/behavior is humane.

"Du meine Güte" does not catch the satirical intent of "Oh, the humanity of it." My knowledge of German is not sufficient to coin a similar expression in German for you, but perhaps my explanation will help you find a good parallel.

FWIW: The only time I heard this expression is in the live broadcast of the Hindenburg desaster in Lindenhurst NY. The radio commentator, watching the Hindenburg come down and go up in flames, sobbed "Oh, the humanity!" into the microphone. Now, he may have been referring to the people he thought were dying on and under the Hindenburg, or then he was just expressing his complete shock and dismay.

I agree with tom_ch. This is certainly a very rare expression. I, too, associate it only with the Hindenburg broadcast and have never heard it anywhere else.

Okay, dankeschön an alle, das mit der Hindenburg erklärt wohl auch das hier:
http://homepage.mac.com/barthold.van.acker/re...
Und wieder verstehe ich etwas mehr von der Welt. :)

After looking over the other explanations, I guess I have to retract the one I offered. I was not aware the express had a real origin in a tragic event. Nonetheless, I am really only familar with this expression used in a mocking sense. See these examples (unfortunately, I can't find find an example to illustrate the precise usage that I most attach to "Oh, the humanity of it"):

"Lois Lane was playing Abba covers almost every day! Oh the humanity of it all!" http://www.cs.ucf.edu/~reinhard/holland/

"I always felt that one of the biggest reasons why today, the mob in Chicago are such an emasculated bunch of little whiny bitches, is that they have never had a casino to play around with. Everyone knows gangstas and mob bosses are spirtually incomplete unless they are standing behind double-reinforced one-way mirrors counting change from slot machines. Oh the pain.. oh the humanity of it all..!" http://www.palit.com/2003_05_18_tkl_archive.asp

"Man! Week after week goes by and nothing. No rumors, no speculation, no false assuptions, not evan a guess as to what the Reds [an American baseball team] are up to? Either all the media's sources have dried up, or the Reds are not doing squat to improve the team! I need some information (I was ok for a while, sidetracked with the Alabama coaching search, but I don't have that security blanket anymore!) I need something to think about! If I don't get some info soon I may have to do the unthinkable, my job (Oh the Humanity of it all!)When do the catchers REPORT!" http://frontier.cincinnati.com/blogs/spring/2...

This expression may be known in America, but is basically unknown in the UK.

Hallo!
Falls noch von Interesse, hier ist, was Wikipedia sagt:
"Morrison's phrase "Oh, the humanity" has become an American meme, most often used in a satirical way to ridicule, diminish and trivialize deep emotional feelings that are part of the human condition. The phrase has also been used in a cynical way to decry exaggerated responses to minor tragedies - examples being on the "Turkeys Away" episode of WKRP In Cincinnati, Heathers, "The Pothole" episode of Seinfeld, the "Simpsons Already Did It", "Cow Days" and "Terrance and Phillip in Not Without My Anus" episodes of South Park, the "Lisa the Beauty Queen" episode of The Simpsons, frequently said by Soun Tendo on "Ranma 1/2", "Couch Potato", on "Weird" Al Yankovic's, "Poodle Hat" album, The Grinch, and in the video game Spore. Morrison seems to have used the word "humanity" or "humanities" to indicate large numbers of people; he calls the crowd on the ground "a seething mass of humanity" before the crash."

Gruß,
Eva

For another example for the use of "Oh, the humanity!", check out the Garfield comic strip at http://www.gocomics.com/garfield/, date February 3, 2011.

Das erinnert mich an die letzten Worte in Melvilles "Bartleby, the Scrivener":

Sometimes from out the folded paper the pale clerk takes a ring: the
finger it was meant for, perhaps, moulders in the grave; a bank-note
sent in swiftest charity: he whom it would relieve, nor eats nor
hungers any more; pardon for those who died despairing; hope for those
who died unhoping; good tidings for those who died stifled by unrelieved
calamities. On errands of life, these letters speed to death.

Ah Bartleby! Ah humanity!