I decided to run some simple comparative statistics on MOH recipients (I guess that's what bored geeks do on holidays). Here are the number of recipients per 1000 casualties in the conflict (Killed and wounded and NOT including noncombat deaths):

WWI: 0.48
WWII: 0.48
Korea: 0.97
Vietnam: 1.23
OEF: 0.28
OIF: 0.11

So in WWI and WWII there was approximately 1 MOH recipient for every 2000 casualties. For OIF there was/is approximately 1 MOH recipient for every 9,000 casualties.

Looking only at battle deaths, the rates change a bit:

WWI: 2.32
WWII: 1.59
Korea: 3.95
Vietnam: 5.19
OEF: 2.10
OIF: 1.16

So in Korea, there were about 4 MOH recipients for every 1000 KIA on average.

Of course, one should not take these rates too literally since the rates for OEF and OIF would change dramatically with the addition of a single MOH recipient. Since there is, so far, only one MOH recipient for OEF, so an additional recipient would immediately double the statistical rates which would put OEF near WWI/II in terms of total casualty rates and near Korea in terms of KIA.

Also, rates per casualty may not be a good way to examine this issue. Anyway, just some food for thought.