American Wars

With news of war in Syria, I wonder how many wars have been good for America?

The Revolutionary War was legitimate and good.  No arguments with overthrowing tyranny.

The War of 1812 was legitimate.  No argument with keeping the aforementioned tyranny away.

The Civil War wasn't a "civil war" because the South did not want to control the Union.  The country was made up of voluntary members of a Union, when the South no longer wished to belong they should have been allowed to leave.

The Spanish American war seems silly in hindsight; had Cuba become a state we would, at least, have gotten something out of it.

As far as I know the Mexican-American War seemed legitimate in trying to prevent Pancho Villa's raids into America.

There are some who think that if America had not entered WWI it would have ended in a draw, no harsh conditions would have been placed on losing Germany, and Germans would not have voted for the political party that gave us WWII.

Defeating Japan in WWII was certainly legitimate, but what did we gain from fighting Germany?

What has been gained in every war since?  I begin to wonder.