I like your suggestion of expoding TVs - appeals to the heart if not the mind. Takes me back to Monty Python's exlpoding penguin sketch.
On your - I think - more serous point, the problem is for the mass market cos like Sony there will always be someone who manages to break the code system. People used to sell the software to recode car radios before they were made vehicle specific and you can buy the sofware to "wind back" elctronic odometers.
As more and more equipment becomes internet-connected it may be possible to implement a system similar to the mobile phone IMEI that could lock out units reported as stolen when they become "visible". But someone would no doubt manage to get around that too.
And B&O's system is not necessarily fool-proof. I know one person who claims the police told him his stolen stuff was "reborn" after B&O gave out the codes to the thief. That was some time back, though, and might not happen now.