Killing wanted militants is simply “easier” than capturing them, said an official, who like most interviewed for this story support the stepped-up program and asked not to be identified. Another official added: “It is increasingly the preferred option.” …
If you cannot capture somebody OR try them and keep them off the street/battlefield - the net result during warfare is that they get killed.
Which option allows you to correct mistakes? Bush's. (You can't correct it when they've been vaporized.)
Which option follows more of the rule of law? Bush's. (Detention with eventual trial is WAY better than BOOM. Even with all of the procedural issues around Guantanamo - you can't say that Predator drone strikes are more lawful.)
Don't get me wrong, there are people that simply need to be killed - but you can't say that Obama's drone superhighway is the better, more lawful, more human option.