Oh man, you have no clue man, people here hate that sort of thing and I do to, if I hit someone in the head with a warhammer should it cave in their skull? Most of the time, should claymoring someone in the neck something that could decapitate them? Most of the time. But is stabbing someone in the chest with a dagger and having all of their limbs EXPLODE going to happen? Hell no.
I think realistic decapitations are perfectly acceptable in a game where there are swords and axes.
I think having someones body explode in the example you gave to be stupid and pointless. So in short I agree with your point.
Maybe a destruction spell for it would work better though as magic would give a logical excuse for it.