That's far from guaranteed to work. And are you going to be paying for the F-16s on hot standby around the country?
Really, though, that was more of a glib remark. The more salient point IMO is the fact that the military is far from guaranteed to succeed in bringing down a hijacked airliner before it hits its target, or without killing other people on the ground.
Besides, since 911 the doors of plane cockpits are almost like a bank vault.
:(