Why no dust cover?

I have seen several Duster 340s WITHOUT the bottom bell housing dust cover or starter dust shield. In fact, when my wife and I bought our '70 Duster 340 it was the same way. The 2nd owner of our car weekend drag raced it at the local, small town dragway in 1973.
Q#1) Was this just for removing weight or what?
Q#2) Does anyone here on FABO run their cars that way?