Cat Ds are stolen recovered so there's normaly there not damaged or have minimal damage,.
Cars like that should be crushed without question.
Id rather not call for the crushing of all repairable cars on the basis that one was repaired badly and crashed for a bit of pop journalism, the cynic in me wonders if perhaps they did a bit of selective testing to get the result they were after...
Its also a very short step away from demanding all cars over x years old should be disposed off as possibly corrosion may have weakened the monocoque in unseen ways.
A proper repair will be as strong as the original car was, if its seam welded in place instead of spot welded it could even be stronger.
We're throwing things away on a whim too often as a species as it is without mandating the production of extra waste.
I think the rating system works well, in that a repaired car is identified as such and allows you to then make a informed decision on the quality of repair, and if you cannot, you can take the option to take it to someone who can.
If you mandated that anything that had a repair to the chassis was to be crushed, there would be about 2 vw campers left in the entire country. And probally 0 Range Rover classics...