ATS units in the UK do receive PIREPS and do pass them on.
Ever read a sigmet like - "Mod ocnl sev turb obs....."
Remember that the only way of observing icing, turbulence and to a large extent windshear is from the aircraft in flight..........thus the met office rely on PIREPS especially with regard to these items.
As I said, Pilots can't moan about the lack of data if they refuse to do their bit!
Regards,
DFC