[Arctic]

Hi Maninder.
It is definitely a design fault as the plate which holds the nut inside the panel is only spot welded, which in turn flexes at that point it, the flexing then weakens that part/area, it does not only fail towards the cars life span as these have failed on cars that are only 3-5 years old, in my opinion I would say it depends on how many times the tail gate is used over a time.

A car that as most likely never had the car tail opened very much would not have the same strain as one that was opened every lets say to take out a kids buggy, remove items from the boot maybe a sales person whom as to remove sample of items numerous times day.

When the part does fail it does with out warning it does not gradually fail so you can see the crack it fails with quite a load twang, in my case the gas strut shot up and over the rear roof scratch a deep line on the roof which also had to be repaired.

You can see from the photo below that the Tourer I have now as had the same problem when I don't know but only one side had been repaired and not that good either so something that will need addressing in the near future.