If bags already have locks and zips, is there really any point in covering them with layers of plastic wrapping?

It's a thought I'd wager many other travelers have had, too. Here's what I unearthed about wrapping your luggage in plastic. In the United States, the cost of wrapping a single piece of luggage ...

Some people wrap their luggage in plastic while others buy protective cases to hopefully mitigate any dents or marks.