It is kind of unprofessional how they change their mind so quickly. Clearly driven by them trying to get the S/X sold quickly. Nothing wrong with that, that's what every business should do, make good sales and be successful, but this change of mind so many times doesn't build long term trust in the brand. Same with the complete 180 on the referral program.
Having said that, the cost of Supercharging is really small. It's roughly as much as you would pay at home, so it's not like you are getting ripped off at a Supercharger. Unless you drive a lot of miles on Superchargers, it's a small expense. I would not decide to buy or not buy a certain car or model year based on that. For example, if I had the choice to get an old car with free Supercharging without AP, or a newer one with AP and paying for Supercharging, I would pick the new one. I think the same will be true for the 2018 Model S/X. It will be a new car with lots of fundamental improvements that are worth more than free Supercharging.
I would also like to add that in the beginning, unlimited Supercharging was $2000. That is the equivalent of 40-60k miles.