Media coverage, the possibility of a class action lawsuit (demanding a vastly extended warranty, as well as reimbursement of money paid out of pocket from victims that this happened to out of warranty), or even just individual lawsuits, might help bump VW/Bosch into either fixing the problem, or at least admitting there is a problem and doing the right thing for customers.
Of course, I'm sure their bean-counters are well aware there is a problem.
While the failure rate might be statistically low, there has been more actions on less impact before. (Think - Toyota gas pedal recalls? The difference is, brakes CAN still stop the vehicle even if the engine was to be revving at full speed. But once the HPFP goes out, you're done)
There is sufficient evidence that they know this would be an issue. Even Bosch's own slides have shown they KNOW that fuel lubricity in the US does not meet even their own recommended levels. They KNOW that product is being put in US cars.
If you know you're putting out a product that is crap... what leg do you have to stand on?