I see the argument by some as a legal one, not a moral one. The morality of drones, war, preemptive strikes, white phosphorous, land mines, and so on are one matter ... law is another.
US citizens are afforded, by law, certain rights and US government, by law, is constrained in its actions towards US citizens.
Matters of due process, presumption of innocence, jury of peers and so on appear to be tossed under the bus with drones. A war posture is the claim to allow these actions, but as the "war on terror" has been declared by consecutive presidents it be a permanent state of affairs as opposed to more obviously described wars in the past, it would seem the executive has expressly stated that the rights of the accused are now permanently void.
A rather significant chunk of the constitution is thus voided, and voided permanently, if we are to take the current and previous CiC at their word.
It would seem that is legally significant.