Affairs and Resignations

General David Petraeus resigned as CIA directory today because, he said, he had an extra-marital affair. Was this really necessary? Obviously I don't know the whole story, only what Petraeus put in his letter. But I find myself agreeing with Sen. Diane Feinstein, who said "I wish President Obama had not accepted this resignation. . . [which is] an enormous loss for our nation’s intelligence community and for our country."

Suppose all of our leaders who had affairs had resigned. We would have had to do without Thomas Jefferson, Benjamin Franklin, Grover Cleveland, Franklin Roosevelt, John F. Kennedy, Robert Kennedy, Ted Kennedy, Dwight Eisenhower, Martin Luther King, Lyndon Johnson, Bill Clinton, and that's just the ones I can think of off the top of my head. Would we be better off without all that they did? You can hardly take a walk in England without bumping into a statue of Horatio Nelson, whose behavior with his mistress raised eyebrows even in the tolerant 18th century. Should we take them all down, perhaps replacing them with more statues of the less amorous (but politically reactionary) Wellington?

UPDATE

I see that conservative rumor-mongers have been all over this one, suggesting that Obama's operatives forced Petraeus out because his upcoming testimony on the Benghazi affair would have been so damaging, or something else nefarious:

Why would an affair mean that he couldn’t run the CIA anymore? Was he being blackmailed? Or is there more to it than this? …Petraeus’s resignation letter says, “After being married for over 37 years, I showed extremely poor judgment by engaging in an extramarital affair.” But Petraeus has actually been married for more than 38 years; the wedding was on July 6, 1974. In other words, if you read the resignation letter carefully, he’s telling you that this happened sometime between July 2011 and July 2012, not recently. Why didn’t he resign sooner? Or, on the flip side, why didn’t he try to hang on longer if he’d held on this long already?