As an IT Architect, who daily works with and for those with varying degrees of technical skills, I would disagree that the user is "an idiot". The steps you mention will certainly address the issue no doubt. What is in question is if the layperson should be aware of these steps and be capable of undertaking them "if" they forget to disable iMessage. What a class action lawsuit will do is force Apple to put in checks that look at the IMEI of the phone each time an iMessage is sent and the ack isn't received by the server from the phone in x amount of time. There is a different error message for an IMEI either offline or registered to a new user than one where the phone is simply unavailable. I can think of 5 different ways Apple can identify the device changed to a non Apple device. They haven't fixed this issue on purpose. Creating an issue like this undoubtedly ensures a percentage of users return their Android phones and get another Apple device to fix the texting issue thereby ensuring Apple revenue. You can bet Apple will weigh the cost of the suit versus the customer retention revenue and either pay out and leave it the way it is or fix the problem. There's no doubt it is a problem because it's not automated and the courts will rule in favor of the user because the process is not automated.

As long as the push start systems have the ability to remove a key from the fob and remove the push button to reveal a manual key entry to circumvent the push start system then yes. That gives both worlds and a way to start the car in the event everything related to the push start system fails. That's how my car works now and how every other car I know of works when it has a keyless start.