The American form of government relies on effective checks and balances between the three branches of government. If the Executive branch establishes a precedent of bypassing the other two branches in this way it is a rather worrying development for the US Constitution.

And, moreover, this sort of behavior is the very thing the US criticises in developing countries. Even if the Executive Branch IS only using this for the so-called WAR ON TERROR, it still, ironically, makes the world generally a less safe place, by providing moral cover for axis-of-evil sorts, including islamist regimes, and makes it less likely that the US government will get support from governments and organisations that might otherwise listen to the US when it calls for condemnation or action against anti-democratic nations.