For most people, I think the reason boils down to three words: beyond economical repair.
We're beginning to see this more and more with petrol A2s in particular; they're considered 'high mileage' sooner in their life, they're less sought after and much more abundant than their TDI cousins. As a result, their prices have now come into a zone where they're falling victim to this phenomenon.
I really like what you're saying, as I also enjoy restoration and seeing A2s being kept alive. The phenomenon that we're seeing is an inevitability though, so I think we've got to make the best of it. If the death of an A2 breathes new life into another, then not everything is bad. If goodies are distributed amongst those who desire them, then remaining A2s are improved and further cherished by their owners.
As you know, the A2 that I broke was absolutely dripping with toys; many people's cars benefited from it being dismantled, including Humpy, either through replacement parts or added spec'. It was a wreck. Its 1.4 petrol had done 150k miles and was weeping oil all over the place, its clutch was slipping appallingly, its CCCU had gone nuts, there was oil-based paint spilt all over the interior, the suspension was ruined, and it'd been involved in minor a front-end shunt that destroyed the front bumper area. It was a lost A2, and I'm glad it fell into my hands rather than the hands of a certain Cambridgeshire-based company. All the same can be said of the A2 that you broke.
I agree with your point though, Tony. Breaking can make a few bob, but so can restoring a vehicle. Choosing whether or not to break a particular A2 ought to be done with consideration and a sense of responsibility for the wee car we all admire.
Tom