Some people here like to claim that "the bad playfields are only a tiny percentage and it's all blown out of proportion".
If that's really the case, then Stern /JJP should have no issue/problem replacing the playfields on that "tiny number". The fact that they can't / won't means that they realize that if they replaced all the bad playfields it would cost a fortune.
This is further proven by the fact that even those who do get promised (an unpopulated) playfield end up having to wait months/years for it to be re-made. If it was only a tiny number of playfields there would be enough spare playfields available to send out to those "few" people.
With any big/expensive product (i.e. cars, refrigerators, etc.) there will be a small number of defective ones that get through. It's how the company handles those problems when they arise that matters. Stern and JJP have shown clearly that they have little to no interest in standing behind their products.
Partly this is due (as has been stated above) that they (at least in Stern's case) have a long history of selling to operators rather than end users. However, they have now moved into the (potentially more lucrative) area of the home user - allowing them to significantly increase their prices for "Premium" models. But that lucrative market also expects a far more responsive support structure, which Stern/JJP have not stepped up to provide.
The "cargument" has been made a thousand times, but more realistic is a "frigument". If you bought a $3000 refrigerator that didn't work, how would you feel if the manufacturer said "well, we'll send you a new compressor, but you'll have to install it yourself. And we don't have any spare ones for your model right now - but we'll send you one the next time we re-make your model. Probably in about 6 months or so..."