Agreed 100%. And because you are used to working with manufacturers, you also know the real answer is don't put out shitty playfields. We all know that Stern is capable of putting out amazing playfields, and each time we start bitching too much, they pop out a title or two with amazing and durable playfields. And we all slap ourselves on the back that we "made" them make better playfields.
When I see that, I am pretty sure that means the cost of doing putting out amazing ones is higher, and so it is more profitable to do the less durable ones and deal with the cases where they are so poor they need to be replaced. I don't know their cost structure, but I see their actions.
This happens everywhere. Products get scaled back until the failure rate becomes more costly to deal with comparted the cost savings of a worse product. Whichever cost is lower, that is the one they will do. They are a business, so they have to.