Quality control is great, continued improvement is not always such a good thing. It makes thing obsolete to fast. I own a 2002 Kawasaki Vulcan 750 that was first designed in 1985. My '02 is EXACTLY like the '85 model, other than paint colors. This model was made through '06, with NO changes other than paint. Parts that fit an '06 also fit an '85. I have owned two of these bikes, both bought new. A '93 and an '02. The '93 was sold with over 80,000 miles on it when I decided I wanted something else. The something else didn't work out, and I went back and bought another new Vulcan 750 without even considering anything else. It now has over 77,000 miles on it. I intend to wear this one out, if I last long enough.
Continuous improvement to me is just another term for planned obsolescence. It means the constant need to redesign something that was working fine to begin, and results in totally out of control parts proliferation.
I can understand why a dealer will not work on a really old bike, they go by the book on labor, and when they tear into an old bike, there is no telling what they might find. It might cost way more to fix than their original estimate, and possibly more than the bike is worth. The customer might just walk away leaving them with an old bike that is worthless to them.
BUT. Parts are another matter. I think parts should be available for a VERY long time. Lack of parts is why I do not own a vintage Japanese bike (other than my '85 Goldwing, which most parts are no longer available for new) It's why I am concerned about investing even $5000-$7000 in a 1500. No matter how nice it looks and runs, it is still going to need parts, and I am afraid those parts are not going to be there. One neat thing about owning an '85 Vulcan 750 is that ALL the parts are still available, and will be until at least 2016, 10 years after the '06 model was sold.
I know this is a sore subject here, but there is a certain American motorcycle brand that you can get parts for no matter how old it is. That makes it possible to keep it going forever. True, these parts are not made by the manufacturer, they are made and sold by the aftermarket. But, the manufacturers continued use of nearly the same technology for decades is what makes it profitable for the aftermarket to continue producing these parts. There is a market for them. There is almost no aftermarket for parts for most older Japanese bikes, partly because they are constantly changing things. In most cases things that worked fine to begin with, and didn't need changing. Many people continue to own and ride the older Goldwings and find ways to keep them going, because they like them. I'm one of those. And I would still buy parts for them from Honda if they still made them.