Why Variable displacement compressors go bad

I decided to take apart one of the compressors of a Land Rover because I couldnt help but wonder why are they so expensive, and why do they go bad all the time. I took it apart (with high res pics of course) and I decided to share it with the forums.

Here is the link for the pics:

Jaguar HELP!: Variable displacement SANDEN compressors

It turns out what goes bad is a control valve internal to the compressor. (in the last pic)