[xwdv]

I see a very strong reason. It’s not lifespan that matters, it’s attention span.

You could build a device with a 1000 year lifespan, but it’s a waste of effort if the consumer wants a new one after 5 years. It’s optimal to build a device with a lifespan that will only be as long as a consumer’s interest in it.

[usrbin]

Fair. Keeping in mind real-world consumer behavior matters to the equation.

That said I don't know that we should assume that "build for longevity" and "build for effective disposal" are mutually exclusive.