Are you sure you are reading things correctly?
Unlawful combatants: Defined by the Rules of War as those who wage war without uniforms, without carrying arms openly and/or who willfully target civilians.
Examples: The German commandoes who were captured in American uniforms during the Battle of the Bulge and executed. Iraqi jihadis who fight while posing as civilians or who use human shields and who can be executed rather than be classified as POW's if they are caught while still alive.
Are you sure you mean to say that you are against the Rules of War stating that they can be executed?
The original question is why go to a known terrorist's house and capture him instead of simply dropping a JDAM on his house.
The answer was that the terrorist could have a gold mine of intelligence information that can be very useful. Saddam, for example, was captured with information provoded by one of his henchman that was captured instead of just killed.
If the terrorist deserves killing after interrogation, the Rules of War provide for that as they allow the execution of unlawful combatants. Example: The execution of Nazi and Japanese war crimminals after the end of World War II.