And being produced by the federal government, unencumbered by copyright.

It wouldn’t surprise me if you couldn’t distribute the form globally due to US export restrictions to Iran, NK, etcetera. Obviously not a problem for Apple since it is already restricted/tainted.

It's in the public domain, so the limits are not on the content itself. The media, and the facilitation of the transfer might be limited, but this is a question for the legal department, which I'm not part of.

But changes every year.

If you're not using for it intended purpose, do you actually care which version of the form you use?

Older versions might be difficult to get in the future, difficulty reproducing results due to that, yadda yadda.

It works for most cases, but I can see why changing every year might be a deal breaker for some.