To each his own, but it is completely unnecessary to sand them smooth. A few layers of good seasoning and they will be just as non stick as the vintage stuff with proper cooking methods.
I agree with you but this had what looked like welding splatter chunks of metal on the inside that protruded sharply about 1mm in many places. It was impossible to use a spatula. My thought was that the pieces could break off at some point in the future and break a tooth and/or result in an exposed portion of metal that wasn't cured.
That and I just like to tinker. :-)