Because peace games tend to be dull?  And actually participating in war is dangerous? 
 
  
  
SO you're saying that somehow playing a compouter game somehow simulates the actual dangers of real war? 
  
  
Is that with the health pickups?  Or the regen? 
 
  
Yeah, pretty much.  Most video games attempt to offer people a glimpse into a life other than their own, whether or not it's a good simulation.  Also, if you have a problem with glorifying war, chasing video games specifically is barking up the wrong tree.  Movies and books on war have sold like hotcakes long before CoD 4.