If you disagree with the policy of extra-territorial targeted killings of terrorists, then Congressional oversight should be a tertiary concern, at best. Internal accountability ought to be secondary. You might well be concerned about more significant values: International law, or about transparency, or about democratic responsiveness.
You might as well wonder why Congress will not permit the administration to develop a detention and trial system that would allow for more "capture" missions. And why does the U.S. rely so heavily on foreign intelligence organizations for targeting information? In other words, your focus ought to be at the top: On the policy itself.
You need to learn what happened on December 17, 2009, when the United States and Yemen jointly launched an attack on what their intelligence told them was a group of al Qaeda on the Arabian Peninsula combatants in Ma'Jalah, in Yemen. As The New York Times and other organizations have reported, at least several dozen innocent people were killed, many of them children. The administration has not been held to account for this, even though U.S.-made cluster bombs and cruise missile parts were found at the scene, and even though, in private, officials conceded to some national security reporters that the Special Operations Command planned this particular strike, and that the president's top legal advisers signed off on it. The intelligence that al Qaeda operatives were in the area was based in part on Yemeni human sources and in part on United States signals intelligence collection.
This is President Obama's policy. If he or a direct representative signs off on every strike, then he deserves to be asked about every strike that goes wrong. Realistically, he cannot and should not be booted out of office, but he can set an example for his successors. So can journalists and political activists, who must ask future presidential candidates about how they'll hold themselves accountable, and just precisely what their policy is when it comes to killing terrorists overseas.
Ironically, the era of high-profile kinetic strikes may be coming to a close. The administration has begun to shift its thinking away from killing the bad guys and towards helping host nations solve problems through creative and non-kinetic means. This suggests, to me, that President Obama recognizes the consequences of collateral damage, and that while it may resort to "drone" strikes when necessary, it will renew its efforts to capture and detain wanted terrorists, and then try them, either here in the United States or in the country where they were captured. He blew his chance during his first term, not standing up for his Attorney General Eric Holder when Holder wanted to try the 9/11 conspirators in federal court. Obama has three years to rectify his error. Putting military action back in military hands is a first step.