I don't begrudge that one line of boilerplate just so its absence enables a couple of decades of non-breaking backward compatibility.
While I strongly believe good code (and good protocols and good file formats) should include a version number to disambiguate meaning, it's always felt backwards to me that the burden is on users of new releases to enable new, non-experimental things to prevent users who don't update their Perl from having to update their code.
I heard just this week about a company migrating from Perl 5.8 to 5.26 or 5.28. That really doesn't feel like the most important group of users to optimize for: people who want a new Perl every decade-plus.