Because it would finally make a distinction that Democrat philophy followers always want to avoid: that of separating Felons from the rest of law abiding society. Because it would penalize and cause a new Felony conviction for each Felon who attempts to lie or deceive on the Federeal BATF Form. I'm sure the liberals of the ACLU would decry such "labeling" and targeting of a specific group of ... (wait for it) CRIMINALS.
Because it would make far too much sense to target the criminals who attempt illegal ownership and go around EXISTING LAWS. Because the Democrats want to continue the lying myth that there are virtually "no laws" stopping gun ownership and it allows them to demonize Republicans, Libertarians, Conservatives, the NRA or other gun rights proponents as if they are the criminals, for supporting their God - given, Constitutional RIGHTS to defend themselves (including against an increasingly unconstitutional, overbearing and tyrannical government) and prevent the very unconstitutional power grabs that so many liberals dream of, like the mass - disarmament of millions of Americans, in a dramatic, "new deal" they are eager to begin.
The Democrats are far more interested in centralized government that reduces some rights, like the 2nd Amendment, while hardly batting an eye when 1st Amendment rights to free speech are routinely squelched, if it doesn't follow their fascist, socialist point of view on college campuses, because an educated, armed, Constitutionally savvy and informed populace is a danger to all the socialist, liberal takeover hopes they posture and keep trying to push onto the rest of us, all in the name of "saving the children."
Because making real laws tougher on real criminals, FELONS, is going to crack at their foundation of criminalizing ALL patriots who want to defend themselves - after all, making criminals of everyone with an independent thought and civil liberties to defend themselves is easier than actually enforcing the law against the hard core criminals, many of which they want to aid in being able to vote Democrat.