I guess this the the real problem.

That Stern is changing to SMD and node board systems is not really much of an option for them. Any other production method is getting more and more expensive as it get less common.

New technology is not really meant to be serviceable, and it does not have to be as it's very cheap. Often the devices are even glued shut. My first VCR cost 2500USD back in the day, today you can get a full fledged media box for 200USD and less that has x times the functionality.
This isn't a problem as if the device breaks within the guarantee time (in Europe 2 years by law), they just replace it. Repairing these things makes no sense as failure rate during this time is rather low and replacement is dirt cheap, especially for the manufacturer.
If it breaks after the two years most likely there will be even better media boxes with more features and even cheaper than the original was or any repair could ever be.

What Stern is doing is using the advantages this new technology, but not applying the market rules that come with it (cheaper products with each new generation to make serviceability unnecessary).

But you can't really blame Stern. The customers are the ones who make this possible.

Everyone is whining over these things and quality problems and less mechanical features, but whenever a new pinball machine is presented pretty much exactly this happens :

I firmly believe this is the case. But I have to admit I'm not as surprised or bitter about it as others seem to be. Maybe it's because I have to deal with financial investors on a daily basis?

They needed an investor and got one who is not coming from the pinball business. He was hired to make them profitable again and maximize earnings - this is exactly what is happening. The focus shifted from the product to the business model.

The investors success is typically not measured in sustainability but rather in "how much was gained until day X" (which is common in the US, but being German it's still a very strange approach to me). Who knows what the pinball market or general economic situation will look like in 10 years from now, so cash in as much as possible while "the good times last".

It would be interesting to know Gary's future plans. Is he already preparing to sell his company mid term and making it attractive to potential buyers by being able to present huge profit margins? Does he even have to care what happens to his games in 10 years from now?

Which part?

Spike is the system used in Sterns 2013 "The Pin" models.