I don't know of any specific product or instance where something was specifically designed for early death. Anyone postulating such should, at a minimum, suggests candidates and some explanation as to why and how it was designed to fail.
But, it might well be that gear is designed and built without sufficient consideration of longevity and the availability of replacement parts. Planning for future unavailability of parts means stocking up on replacement parts, which is a considerable expense that must be be built into the price of the component. Some manufacturers do stock replacement parts for a planned future of serviceability of a certain number of years (a practice of NAIM, and Linn, for example). Certain types of components have inherent advantages in this area, such as tube gear with circuits that do not employ anything but basic parts that can always be found.
Most manufacturers do, for marketing reasons, tout new models and designs and claim superiority of new vs. old. That is the nature of the market for almost any consumer products--even mechanical watches based on ancient (timeless?) technology, claim ever superior refinements of newer models. But, with amps, linestages, speakers, and turntables, there are plenty examples of very old components that can compete with ANY modern examples when it comes to satisfying certain sonic preferences (e.g., large horn-based systems built around Western Electric compression and field coil drivers). Even modern high end DACs may be built around some very old chipsets that deliver good sound.
I agree that there are some modern designs with sound that catches the ear because of the impression of detail, speed, and impact, that may become fatiguing to SOME listeners over a long period. This is a matter of taste, but not some sort of conspiracy to make one go back to buy something else--how would the manufacturer of such a fatiguing product get that buyer's new purchase dollars? I too don't like a lot of modern speakers and amps--too thin and lacking in body and weight--but this is a matter of personal taste; I don't see manufacturers as promoting the wrong kind of sound; they simply respond to the market demand. If buyers are becoming less discriminating so that they more easily for superficial pizzazz of certain kind of gear, I don't think it is the fault of manufacturers offering that kind of sound to compete. This is all part of a longstanding change in the market for audio gear--less people who care enough about sound quality to listen long enough and to hear enough products to become a more experienced listener not seduced by superficial appeal, and fewer old time dealers that can provide the opportunity for prospective customers to attain that education.
