That ship already sailed way over a decade ago (or longer) and changing it now would just massively add to the confusion between what Perl 5 and 6 are. You can't retroactively rewrite every webpage and reference in history, and it's not a particularly hard to explain that they're essentially separate languages. Perl 5 will continue to be maintained and evolve in a compatible way, and Perl 6 is a much different language altogether. They quite literally "forked perl 6, and continued developing perl 5".
Forking an existing, newer language just so you can do what amounts to a meaningless, useless major version bump of an existing, established language, is pretty much the exact definition of a breaking change for frivolous reasons.
Forking an existing, newer language just so you can do what amounts to a meaningless, useless major version bump of an existing, established language, is pretty much the exact definition of a breaking change for frivolous reasons.