It absolutely had to happen and, contrary to popular belief, it had to happen as a direct result of 9/11.
"It?" The war?
9/11 was just a convenient excuse for a war that had already been in the Neocon plans for some time. 9/11 was a Klein moment that several different interests took advantage of.
Western Civilization was poised to enjoy the greatest economic and social prosperity in all of human history - something this world had never and now, sadly, will never, see again; Middle Eastern Islamic fundamentalists who desperately wanted to see an Islamic fascist caliphate take place decided to directly and successfully destroy that possibility by crippling the centerpiece for the world's most advanced economic system and killing thousands of people in one day (and thousands more on the roads in subsequent weeks and during the ensuing two wars).
You think 9/11 was an attempt to cripple Western civilization?
What was the US supposed to do in response? Just sit back and say "oh well, I suppose they have a point there..."?
The US should have done what it did the first time the WTC was bombed by Islamists, in '93: Investigate the crime and arrest the criminals.
Why should tens of thousands of completely innocent people be condemned by declaring war? How is that morally justifiable?
Middle Eastern Islamic fundamentalists brought it on themselves and the war was the best possible response to those attacks that the Western world could have produced.
Trillions (and counting), in costs, a middle East in chaos and a police-surveillance state at home is the "best response?"
A little Panglossian, wouldn't you say?
The real tragedy is that we didn't stay there permanently and begin colonizing that perennially toxic region for our further benefit.
Conquest and occupation frequently ends up an expensive morass. Our empire is already overextended and sapping our economy. Have we learned nothing from history?
How do you morally justify a predatory war?
George W had an interesting presidency too. In a few decades, people will look back on him fondly as a guy who had a lot of cute screw ups when talking to the media (and will go down as the worst public speaker in all US presidencies) but otherwise managed extremely well and bravely in the face of what could have been a catastrophic disaster.
"Could have been?"
How would you characterize the Iraq war and its continuing consequences, if not a catastrophic disaster?
That was not an issue anywhere near as important as it was made out to be. Iraq had to be toppled for the good of the world and we were right to reap the benefits of toppling them.
Spoils of war?! Seriously?
The US has rarely exerted itself for "the good of the world." I don't remember us rushing into Cambodia, Darfur, Rwanda or East Timor. I don't see us rushing aid to Yemen or South Sudan.
The US does little if it (or certain special interests) can't make a profit on the deal. As a matter of fact, it often installs and protects repressive despots willing to give America economic or military favors.