Re: Why the change?
The spontaneous fire of the car in China that's widely reported is a suspicious case. Tesla put out a software update long before the car was able to be examined which leads me to believe that Tesla was pushing the limits somewhere and dialed them back a bit to keep the problem from happening again. At least for the same reason.
The over-the-air updates are a two edged sword. I've learned not to play with swords and always disable auto-updates. With the Tesla, you don't get that choice, you either opt-in or get a very different car.