They've added something on the order of a couple hundred billion to the deficit every year, which amounts to about $1.5T since the WOT began, so it's not "small." One can reasonably argue that it's necessary, too.
Still, you're right that it's not the major source of difficulty, and this year's deficit, not to mention the projected batshit-insane deficits over the next 10 years completely dwarf anything the WOT has contributed.
I agree, too, that the issues are systemic, and I think it pervades the thinking of pretty much everybody in the country, including you and me.
My diagnosis is "decadence." We've had the luxury of success for so long that we forget about where money actually comes from. It's easier to be "nice" than it is to be responsible. It's easier to take care of needy people than to hold them responsible for their actions.