I'm guessing Tesla didn't include maintenance in the cost of the car as a way to not have to raise the price they promised years ago. Not the best move, but understandable, and not a big deal.
For instance, companies like Audi charge similar amounts for their maintenance plans. If you're willing to pay up-front (which is what rolling the cost into the price of the car does), the cost drops to $475/year. So, Model S is $62,000 base car, not a $60,000 base car - before rebates.
You can't actually buy the maintenance plan yet, because no Model S is old enough to require its first service.
As for what you get for the $475, well, I can't argue that it sure seems a high price, even if it does cover wiper blades. But, in the overall scheme of things, it doesn't strike me as a sales blocker on this category of car. Gen3 will be a different story, of course.