It's good to be able to disable this option: I use old Android phones as servers and don't want them to reboot every 3 days.
Same for 5G modems. A $50 phone will give you gigabit 5G, but you'll pay $500 to get that in non-phone form factor, mostly because on patents on the 5G tech which are charged differently for phones vs dedicated modems.
I think the main advantage to using phones for random stuff is availability: We here on HN probably have a decent selection of old phones to pick from, so it doesn't cost any money at all to give a new purpose to one.
Don't think old Androids will get this update.