Wait, I might be missing the point.
Are you saying that there should be a federally-issued concealed-carry permit that all states must recognize?
That's interesting, but problematic. Right now, as I said, the federal government does not claim the right to have any say in whether a citizen may carry a firearm or not -- except in federal buildings. As far as the US Constitution and the federal government are concerned, they do not have the right to control that aspect of the citizens' lives.
Giving the federal government control over that -- for positive reasons (because we want a federally-recognized CCW permit) -- establishes the legal precedent that they absolutely do have control over that. When the wheel turns and CCW is out of favor, that won't be such a good idea. The power to create is the power to destroy.