I agree that the radiator would have to take a serious impact to actually damage the radiator, but I was inspired to do that mod because something big enough made a sizeable gouge; Plus look at the discoloration from rubbish flying off the tire, running up the center of the rad; nasty!
Then a few weeks later, my buddy hit a bird that managed to tweak the front of the radiator a bit. I figured a bit of expanded metal would just help out a bit, just in case. Plus it prevents snarfs in the cooling fins.
Cheers,
dp
PS, I can't believe the word -C R A P- is on the vulgarity filter list... sheesh..