I wouldn't say its there own fault for volunteering at all, there are many reasons one joins the army, not all of them being "I want to kill people". From my understanding theres a goodly number of soldiers trying to put themselves through school, pressured into service by parents, or just trying to do something other than flipping burgers for the rest of there lives. For people like that these statistics are quite troubling/sad.
However another consideration might just be that these sort of things are getting diagnosed more these days. IIRC in WW1 shellshock/post traumatic stress was offically recorded as lacking in moral fortitude or some other phrase essentially translating to cowardice. Which created a very large stigma around talking about these sorts of things to ANYONE. In todays enlightened times, people may be able to open up more to there doctors, doctors may be able to talk with the soldiers on a more individual level and diagnose people for these things better.
Bottom line: I don't think the Iraq war is any different from any other war. People die, and the survivors have to find ways to go on living. The only difference is that we now recognize some of the problems these people face in reintegrating into society upfront with a medical diagnosis.
Edit: While war itself is a deplorable thing and should never happen, let me share you a little tidbit from first year macroeconomics.
GDP (a measure of how much a country can produce, and generally a decent measure of standard of living) is equal to C(consumption by citizens)+ I (investement and expansion by firms) + G(governement spending) + NX (net exports)
Government spending (which is created from entering a war) increases GDP by an amount equal to the cash the government drops on the war.
However, the governement spending is passed on to firms and companies, who use it it invest and expand (increasing GDP further), this expansion means more workers are hired (which reduces unemployment) who then use there new income to consume more, inreasing GDP even further.
This means that a round of government spending causes an exponentially large shift in GDP and standard of living due the consequetive rounds of spending. However, this does increase the interest rate some, which cause investement to fall again (called crowding out). However 99% of the time, even with crowding out you still see a exponential increase in standard of living when the government spends more money (to say, buy more bombs).
Of course if you really wanted to get into the nitty gritty, this doesn't actually effect the long run health of the economy and will always be followed by a recession of some sort ect ect ect.
