Because otherwise some of the pragmata will misbehave

No. The pragmas (there is no such word in english as "pragmata"), behave exactly as they should.

That is, the only pragma I use preceding the package statement, strict, functions perfectly both within the package and in the main at the end of the package.

Equally, -w works just fine also.

because then you don’t enclue Perl6 that it’s come across a Perl5 module,

In the increasingly unlikely event that Perl6 is ever a real consideration, I seriously doubt that it will realistically be able to handle unmodified Perl5 modules reliably anyway.

I would fully expect to have to re-work all of my modules for Perl6 to some degree, and that small thing would likely be the least problem of all. But I don't see any sign that I will be troubled to need to do so in the foreseeable future.

and because it gratuitously complicates the tool-chain.

"The tool-chain". What a wonderfully vague strawman that is.

If there are tools out there that rely on such placement--that is neither mandated nor even advised by the language specification--then those tools are broken, "gratuitously" so, and should be fixed.

Would you buy a hammer that required that all the nails you drive with it be vertically oriented, point down? Of course you wouldn't.