The economy is bad and most people say that is their issue. Also wars fought by volunteers don't raise nearly the ire that wars fought by draftees do. However I suspect the main issue here something else entirely.
In 2008 the anti-war crowd elected their choice of president, a peace-loving fellow named Obama. And then, guess what? Anti-war Obama fought the war just exactly like his predecessor, Bloodthirsty Bush did, including a new troop surge. So where the heck do anti-war folks have to go in this election?
I had an experience like this in 1964. I was draft age and candidate Goldwater sounded very belligerent while Johnson sounded much more peaceable. I not only voted for Johnson, I urged others to do likewise. Johnson crushed Goldwater, then he escalated the war in Vietnam.
I was bummed. Once I learned that who was president made little difference in the war policy of the U.S., that issue was no longer important to me in elections. Don't you suppose many people with "Visualize World Peace" bumper stickers feel this way now?