In answer to "what could it hurt?"
Let's see....
1) Would expand power of an already bloated federal government;
2) Would chip away further at individual freedoms, in a country that was theoretically founded on the principle of maximizing individual liberties;
3) Would require additional manpower to run the expanded system, plus cost of hardware and software upgrades, office space, etc (IE it ain't free);
4) Would lend credibility to the antis' claims that guns are bad, and therefore require regulation of a type which is not seen against other potentially hazardous items, and which is definitely not seen against other Constitutionally protected rights;
5) Would lend credibility to the idea that Second Amendment protections should only fall under "Rational Basis," since we aren't even requiring antis to prove that what they suggest would be effective, let alone necessary or least intrusive.
You get the idea. This isn't harmless.