Protocol I and II, 1977 amendments to the Geneva Conventions, have been ratified by 174 and 168 states respectively, with only a few states failing to ratify. The United States is one of the few states that have not ratified these two protocols, despite signing the protocols in 1977, an action which signified intention to work toward ratification. As both protocols are so widely adopted that a number of articles from the protocols are now recognized as rules of customary international law valid for all states, it is only logical for the United States to finally ratify the protocols and signify agreement.
Yes, The United States should ratify the protocol that outlaws the indiscriminate attacks on civilians, they should have done that long time ago. If USA, which is seen as a leader of the democratic world, doesn't sign this protocol, it leaves room for other countries to do the same and in the end the civilians are the ones that pay the ultimate price for this.
It would be an incredibly important statement if the U.S. would ratify the protocol in the Geneva Convention outlawing indiscriminate attacks on civilians. In the past eight years, the U.S. has come under heavy criticism for its drone programs which have officially caused the death of 116 civilians to date. Making a statement against causing the deaths of civilians would help win some favor back in the eyes of the world and, hopefully, symbolize a change of direction and policy.
I think Uncle Sam has intentionally left these two protocols unsigned, especially concerning attacks on civilians. The United States is always one of the first to hold other countries accountable when it comes to war crimes and yet we have this bit of unfinished business. Times of war may very well be the reasoning behind the lack of action.