It's not that you're bringing up historical context. It's that your analogies overreach and don't make your points.
Of course we go to war for our interests. However, prior to Iraq, there was typically an existing conflict. Further, especially in more recent history, we at least attempted to manufacture some military pretext (Gulf of Tonkin, etc.) The difference with Iraq--and it's hard to believe that you really don't see this--is that there was no conflict and Iraq was not engaged in any hostile military action. We simply attacked them because of what the Executive declared they might do (WMDs or no).
The point is that it represents a new thinking and acceptance of the degree of power vested in the Executive. Even the architects of this power grab acknowledge this fundamental difference. See "Pax Americana" from the Project For The New American Century.
Edit: More specifically, see the report: "Rebuilding America's Defenses: Strategy, Forces and Resources For a New Century"
Your rebuttal regarding drones and Nazis falls down even more. Of course if a U.S. citizen is taking up arms with a nation that is openly at war with the U.S. (as eventually was the case), and is actively engaged on the battlefield, then the U.S. is justified in making no distinction between him and the enemy.
But, that the Executive has the right to declare that a U.S. citizen is an enemy combatant and may be killed with impunity is vastly different. You may take comfort in your degree of confidence that Al Awalki was a bad guy. However, the policy does not limit the Executive to targeting only those whom you believe to be deserving.
And, that is the very problem with your brand of thinking. Nearly everyone who ascribes to it does so under the belief that these policies and laws are necessary for "security" and will apply to only the bad guys.
But, that is the very point of our form of government and the Constitutional rights that we once held dear. The government (and worse, the Executive alone) doesn't get to decide unilaterally who is guilty or not. We are all entitled to due process, as "flexible" and inconvenient as that may be at times. It is our protection against the inevitable abuse that will arise in its absence, and it is one of our most powerful protections against tyranny.
None of this makes your case in any event. Your initial argument was that the Executive has no more power than they've had in the past. The minutiae of drones vs. Nazis into which you've waded just speaks to whether you think the Executive should have such increased power. In doing so, you are actually acknowledging that they do, in fact, have it, thereby making my point.
Something else that you may not have noticed is that your historical comparisons--invalid as they are--point to various incidents across centuries in your search for precedent. But, notice that these did not all take place at one time. It is, in part, the sum total of all of these powers and abuses invested in our Executive at once that represents such a vast increase in power.