Americans do not like the Obama Doctrine of apology and appeasement. And they don't want a President who is snarky, condescending, peevish, and small.
By the way, the Marines rode horses in Afghanistan and used bayonets to kill the enemy.
Update: Sorry Mr President, but troops DO need horses and bayonets: How U.S. forces are STILL using 'old-fashioned' fighting techniques mocked by Obama
The President's mocking comment was not quite as effective as it might have seemed - because both bayonets and horses have remained important parts of the U.S. military right up to the present day.
Romney showed himself to be calm and capable, not the warmonger portrayed by the Dem campaign.
I would have enjoyed seeing more of a take down of Obama's Libya debacle or Obama's Mexico/Fast&Furious failure, but in the end that's the job of the press and Congress.