A lot of that is probably down to simplicity, but the fact that it's from a time when electronics were expected to be repairable and maintained is probably a big part of it as well. My Apple II Plus from grade school still works perfectly, and I've done nothing more than simply keep using it.
I recently acquired an IMSAI 8080 that had been sitting in someone's storage unit for the past decade. I used a variac at first to make sure I wouldn't fry any circuits, but it turned out to be in perfect condition, and went right back into action as if it were still 1975.
Meanwhile, my 2009 MacBook has long since given up the ghost—and of course, Apple has no interest whatsoever in supporting me to repair it myself. I wish our technology was still built to last, rather than built to replace every two years when the payment plan ends.
They have more material to play with while they decay compared to modern devices.
Probably not, but same is often true for old computers.
Old hardware is easier to maintain. You can recap them, replace the failed memory chips and even fix cracks in the PCB by just running some extra wires.
You can do same to current modern computers as well, but it's nowhere near as easy.
SSDs require power at least once per 1-3 years or otherwise they can lose the stored data.
If SSD loses critical housekeeping data, it might never work again.
This information needs to be better known. I assumed--and I think many people would assume--that SSDs would be an excellent medium for long term backups. Wikipedia confirms that SSDs aren’t good for long term storage:
"If left without power, worn out SSDs typically start to lose data after about one to two years in storage, depending on temperature. New drives are supposed to retain data for about ten years."[1]
[1] https://en.wikipedia.org/wiki/Solid-state_drive#Comparison_w...