I'm not sure what your point is. There are only a handful of people there with issues. It seems like the same ones having issues with their back covers more then once. To me that is a bit suspect. One of them even admitted he or she actually dropped the iPad. The whole idea for these covers is to take the impact and damage rather then the device itself.
I had a CoverBuddy for my iPad2 and loved it, no problems at all.
Got one for my iPad3 and cracks appeared at the corners very quickly, which developed into chunks of plastic falling out. Complained to them and they sent a replacement but this developed the exact same problems a month or two later so I just gave up.
Note that the cases were not treated harshly, never dropped and the iPad wasn't taken out of the case at all so there's no reason why they should have cracked like this.
I have my own theory however...
The iPad2 case fitted like a glove - totally secure with no give or flex whatsoever. When the iPad3 came out, they released a new version but this time it was sold as compatible with both the iPad2 and iPad3, despite the latter being a slightly different shape. The iPad3 was slightly thicker and the tapered edges had a slightly different profile.
I think that, in their attempt to make one case which fitted both devices, it ended up fitting neither perfectly and there was a slight bit of flex introduced, which is what leads to the cracks forming over time.
Hopefully this will be rectified when they launch their iPad Air cases as it's a unique shape and they'll be made to fit it perfectly again but only time will tell.