Same as we need copyright maximums in the range of a generation (20 years). Having something come out of copy right 100 years later removes the cultural impact that putting a copyright into the public domain has. Primarily because everyone who was impacted by the original copyright is no longer alive. A prime example is steamboat Willie, aka Micky mouse og, really doesn't have any interest in doing much with it because it is culturally stale/mummified/dried out.
Not saying that this shouldn't happen, though. Just saying that people suggesting this sort of stuff should realize that the economic consequences for some businesses would be major.
Not so sure in reality. There's a lot to dislike about Apple and I won't go into it, but as an example, I like their support policy. They promise 5y and usually it's 7y. They do disable features on older phones via feature flags where the performance would not be up to it (like on-device AI lately), but this rather long support does not seem to impact their sales negatively. Arguably it works for them b/c people know they can resell their phones after 2y and still get a good price as buyers know they will get support. I am one who switched from Android/Sony precisely because of this.
The same could be true for opening older phones as some Android makers do unlocking the boot loader and leave it to enthusiasts to port newer Android versions. Many phones get recycled to something different this way (controller for home automation) and would never reduce sales.
On one end of the spectrum are people who insist that the reason phones only last as long as they do is a 100% deliberate decision on the part of smartphone manufacturers to hamstring their own hardware, often going all the way into full conspiracy-theory-level thinking, with timed kill switches and the like. Frankly, I find this line of thought to be bullshit.
On the other end are the people who are talking about smartphone manufacturers using components that are chosen for being small, light, and/or cheap, rather than being durable and user-repairable, purely for reasons of design, practicality, and cost savings.
Personally, I know which side of this I come down on; Hanlon's Razor[0] applies here, as well as the fact that, to the best of my knowledge, no actual timed kill switches in hardware or software—nor anything in the same general vein—have ever been proven to exist. And if not even the lowest-grade independent Android phone manufacturers are putting those things in their phones, why on earth would the likes of Samsung, Xiaomi, or Apple feel the need to do so?