Raises GDP...but you can't eat bullets and bombs, and because you made bullets and bombs, you have less bread.
Lowers unemployment rates...but killing isn't much of an occupation and dying isn't much of a living.
Raises stock prices of arms manufacturers...but at the expense of all other business ventures and activities.
Creates a demand to rebuild what has been destroyed...but that only gets you back to where you were yesterday and does not build your future...destruction never beats construction.
Want to honor the dead from past wars? Prevent the next war.