I respectfully suspect you are misunderstanding history. First, the Copyright Clause permits, but does not mandate, certain forms of creative protection for a limited time.
Second, the clause itself states its goal. It was to encourage more creation, "preventing piracy" was a means to an end, not an end in itself.
And finally, there is good reason to think that regarding copyright in particular the target was never meant to be users at all, but other commercial grade publishers and competing authors. (It was prohibitively difficult in that era for an end user to make a copy of any substantial creative work so it likely wasn't even considered. I suspect, given some of Jefferson's comments in particular, that many of the Framers would have been against trying to apply copyright laws to end users had they realized it would eventually be an issue).
Second, the clause itself states its goal. It was to encourage more creation, "preventing piracy" was a means to an end, not an end in itself.
And finally, there is good reason to think that regarding copyright in particular the target was never meant to be users at all, but other commercial grade publishers and competing authors. (It was prohibitively difficult in that era for an end user to make a copy of any substantial creative work so it likely wasn't even considered. I suspect, given some of Jefferson's comments in particular, that many of the Framers would have been against trying to apply copyright laws to end users had they realized it would eventually be an issue).