One of the reasons I was one of the first to buy a Tesla is because I love the fact that Elon Musk refused to abide by all of the known "rules" of automotive manufacturing. I love it that I get regular updates to the car's firmware/software that actually adds features to the vehicle (one of the first ones I got actually made my 0-60 time faster!).
But I think that when it comes to this idea of not following the established rule of "model years", it doesn't work very well. The modern-day method of rolling software updates is great--for software. But when it comes to hardware, it is a bit more difficult. It's made even worse when things are not retrofittable (like the rear seat heating referenced here).
I understand that the company has a great new hardware feature and wants to get it onto the assembly line as quickly as possible, and you have to applaud that. But you end up with people ordering a car and not knowing what they will get. Some improvements are announced at or around the time they hit the assembly line, and many cars without the improvement are then delivered for a period of time. Note that although the summary only references "options", there are many more improvements other than options that are added in an add-hoc manner.
We haven't even seen the confusion this will eventually cause when there is a substantial resale market for the Model S. There will be no "shorthand" to say what features the vehicle has or doesn't have. Even the Roadster had "version numbers".