Why would you want troops' lives to be in any more danger that they have to be? Your "ethical" consideration are mighty thin. You can bet the other side doesn't worry about prissy rules when lives are in danger. And Congress has every right to worry about ours.
They represent the people and are directly elected by them according to the Constitution. There's a reason for that; soldiers don't renounce the Constitution when they join the service and the UCMJ is made uder autority of the Constitution.
Imagine you're a soldier and you hear that enemy collabarators can't be made to reveal known dangers to your life. You just have to suck it up and get hit by every planned ambush at any time.