On the face of it, Wino has a solution to counter the horrific events of the last week. But as spagiola has written, the solution to one problem is usually never an improvement across the board and can be detrimental in other areas.
On shooting down airliners, there have been at least half a dozen aircraft coming back over the Atlantic over the last couple of nights who have made initial contact which has then been lost. One business jet was incommunicado for around 45 minutes. Airborne relays, calls on 121.5, SELCAL requests, not one of these was able to raise him. His route to Europe was not far from passing over the RAFs Northern Air Defence station so any shoot down policy would have been pretty quick to implement. Finally getting two-way as he coasted out from the UK he declared he had some 'radio problems' (technical term for volume turned down, radio turned off, or pilot asleep ?) I regret to say that the other 5 aircraft were either United or American Airlines. Sorry guys, but in these heightened times these two airlines are the ones I would expect to be totally on the ball. Other aircraft in the vicinity were communicating OK so I don't think it was a 'technical' problem with the frequencies in use. As you might appreciate, the military are certainly interested in aircraft losing communications these days, especially in the circumstances described. Fortunately two-way was eventually re-established in each case before too many cogs in the system began to turn.
On flight deck access, the BA BAC 1-11 was another classic case where life may have been lost without the cabin crew being able to get in. The Captain was almost sucked out the aircraft via a cockpit window but was held in the aircraft only by one of the male cabin crew until landing.
Wino's idea is certainly worthy of consideration but can't just be looked at in isolation.