This is a little short sighted I think. Apple have been in this game for long enough and would have known about this potential issue. They chose to roll the dice....and they lost.Thirsty lawyers and idiotic users.
When it comes to user experience it's a double edged sword. You either tell your user everything and overburden them with options (essentially turning into android) or risk lawsuits by just doing what is in best interest for your end users. However... what this isn't, is planned obsolescence... There are far easier ways to do that if they really wanted to which could not be pinned on them in court.
I think people with their phones rebooting would be more likely to buy a new phone than people with phones that continue working albeit a little slower occasionally. Apple actually extended the life of the phones and not made them obsolete. Only thing they did wrong was not be transparent enough about it.
I guess a disclaimer like "Your phones battery is degraded, your phone may run slower because of this to allow continued operation." would be all it took to avoid this. It's just hilarious how people think they caught Apple doing something against them not understanding the complexity of this situation.
This is why we can't have nice things.