The New York Times baldly says why (bolding mine): "One day before President Obama is due to deliver a major speech on national security, his administration on Wednesday formally acknowledged that the United States had killed four American citizens in drone strikes in Yemen and Pakistan." Best to have that finally on the record before said speech, eh? - Particularly since the administration needs to tread the difficult path of following George W Bush's basic counter-terrorism policy while still roundly criticizing George W Bush's basic counter-terrorism strategy*. Thus pleasing nobody, but then this administration has rarely shown any sort of concern that their actions might be offensive, annoying, or (these days) even comprehensible to others. I understand that it's part of their, and I use the term loosely, 'charm.'
Also, note this bit from Eric Holder's letter justifying current administration drone policy:
Holder is probably a little resentful at having to leave that bit off of the table (thanks in no small part to Senator Rand Paul); this administration hates any and all suggestions that there could be any checks to their naked will. But then, the rest of us are quite resentful at the way that this administration seems blithely indifferent to the way that their policies keep getting people killed in avoidable screw-ups, so I suppose that it all evens out in the end.
Moe Lane (crosspost)
So the government accidentally kills three times as many Americans as it kills on purpose? Seems about right. nytimes.com/2013/05/23/us/…
— Sonny Bunch (@SonnyBunch) May 22, 2013
*Although Bush would be - was - a lot less likely to lean on drones as a cure-all method. Because while dead man can tell tales, it's still more cost-effective to ask your questions of people before they become corpses.