Pretty sure they are asking, "Why would I ever want the tracking copied, why is this relegated to a bespoke option instead of being the default behavior?"
I think it's good to have a normal copy along with this remove tracking one. In case for some reason removing tracking messes something up with the link and makes it not work. It's always nice to have options rather than just doing it automatically.
The fact is that there is no surefire way to get rid only of tracking parameters, because they can mix in with other legit ones that if removed would break the website you're visiting.
Last I heard, Facebook had rolled out some encrypted URL parameters, so the collective mapping efforts to manually identify parameters only used for tracking on each different website could very well be nullified if many implement something evil as that