I might not. Establishing a skill or training requirement means setting standards which are, most likely, enforced by whatever government entity the training program installs. With that in mind, think about how the standards can be abused, misapplied, or be unreasonably attainable. If you’re in doubt about this, recall the Southern states and their requirement that black voters “pass a test” before being granted the inalienable right to vote. Having a government arbitrarily decide who does and doesn’t qualify to express his inalienable right doesn’t work.
Well this purpose is firmly stated in the amendment.
Anything on God’s green earth can be abused; it is up to America to keep enough vigilance on itself not to do that, including letting the private sphere be the guardians of the standards. Doctors do not need to pass government examinations to be permitted to practice; it is enough that they pass the examinations of universities that have a cross-accreditation system.