Yeah, they did do that one :)

I can see the advertising campaign for that one already: "Get on the fucking train, Shinji"

I haven't looked it up but I would bet you it's due to fatigue limits. They probably use aluminum a lot which always fatigues no matter how light the stress (a bit like me tbh...) so anything made from aluminum gets retired after a set time period.

The same is true for jets. Each flight expands and contracts the airframe since it's a pressure vessel, and the wings can deflect a large amount too.

500 series is absolutely the best looking, in my humble not-really-train-person opinion.

They're 30 years old after 8 years of operation?

That's somewhat average, I would say. I was actually told that the Japanese only keep their high speed trains on service for about 20 years, this is obviously longer than that. In many other countries, high speed trains built in the 90s are still in service. Mind you, the birth of high speed trains was around 1990, so it's hard to really compare with much. Conventional rail vehicles can last very long, though - rolling stock that is 40 years old or older isn't exactly the exception. Often the problem is less the state of the rolling stock (especially with the older stuff, which was often built more solidly), but passengers' expectations. In fact, passenger expectations changing too quickly for durable, long lasting trains can be a significant issue.

Theyre being withdrawn. They were first built in the mid 1990s.