maybe for us or non military people but I bet the men in WWII felt the same way about killing people and bombing other countries as the men do now or how about watching other soldiers being killed. I don't think those men worry to much about how we rationalize things, I am sure it is a small factor.In one my pych classes I took said one of the reasons this has happened more during vietnam and now in Irag is because they just put them on a plane and they are home in a day or two. During World War II for example they had to come back on a ship and had more time to process everything before they were thrown back into regular life!
plus there was like may be an easier way to rationalize WWII v. the more recent conflicts...
If you listen to them they usually say they feel isolated because non vets have no idea what they went through and what they saw.