If you want to write a "Testing Considered Useful" draft,
go ahead; but I doubt that any implementers who have
ignored the examples contained within the specification
RFCs will wake up and take notice.
If done in conjunction with an online test suite, and a way to report
errors, it might be more useful. That way, if vendors didn't test
their products, their users would. Ideally we'd get IETF to host the
test suite. something like mimetest.ietf.org . though there should be
a backup plan in case this is too politically sensitive.