I don't think that lack of reliability is the key factor for why new motors are still being developed. Fuel efficiency or changing emission standards are two points that come to mind that drive further optimizations.
Perhaps that's what's remarkable about these? They had architectures that could meet 2025 emissions standards, 25 years ago. That said the Honda "L" series engines are just as long-lived and are the even more efficient variety.
My favorite fact I used to tell people when I owned a 2008 Honda Fit was that parts of the L-Series engines was from Honda Powersport's Boat Motor lines. (the crankshaft if memory isn't failing me)
They should do more cross-over technology. Why do they make a motorcycle with a 1.8l flat 6 engine that shares the 73mmx73mm cylinder format of the early L-series car engine, but they can't bring an engine like that to cars? It would be smooth as hell.