Sturdy as it is, the watch won’t last forever. You can replace the battery and the plastic resin watch band, but I’ve found that doing so can be tedious. Since Casio introduced the F-91W in 1989, I’ve owned several, and some of its cousins, which date to the 1970s. Casio called them technological “miracles” back then. It is their continued availability at reasonable prices, not their aging technology, that makes them minor miracles today.

Replacing the originals was my choice over the decades; it wasn’t forced on me by Casio.

“Repairing devices is better for the planet than buying new ones,” said Kyle Wiens, a founder of iFixit, a website with do-it-yourself manuals and other resources geared toward teaching “people how to fix almost anything.” Mr. Wiens contrasted Casio, which makes battery replacement a straightforward if delicate task, with companies like Apple, which directs consumers to the company’s own stores or certified technicians.

“These companies are deliberately making it more difficult for people to repair their devices,” he said. “And they push people to replace existing devices that work perfectly well. That’s planned obsolescence.”

Michael Waldman, a Cornell University economics professor, expanded on that idea.

“I would define ‘planned obsolescence’ as the practice of coming out with innovations more quickly than is efficient from the standpoint of social welfare,” he said. “For a company, it’s a way of maximizing profits, perhaps at some cost to consumer welfare.” By that definition, he said, Apple is engaging in planned obsolescence, while Casio is not.

Consider what will most likely happen in the fall, when Apple introduces new operating systems. The company says iPhones that can handle that update will be able to operate in “dark mode.” That should cut back on emissions of light and, perhaps, ease eye strain.

I’d like to use dark mode but I can’t, unless I reach for my wallet. That’s because my iPhone 6, and older iPhones, won’t be compatible with iOS 13, the forthcoming version of Apple’s operating system. Owners of older iPads will be in a similar predicament. And owners of new Apple Watches but older iPhones won’t be able to update their watches unless they get a newer phone.

How bad will this be for consumers? In an email, Apple said, “We work hard to provide our users with exciting new features every year while maintaining performance,” adding that “this is a difficult challenge, and at some point we need to stop updating older devices so we maintain a good user experience with strong performance.” Even for those older devices, the company said that it would issue security updates it deemed critical “on a case-by-case basis.”