I can see why you are upset about getting a headliner different than what you expected. And yes I think it was somewhat crappy of Tesla to change something so visible without giving people a heads up. But think about these questions before you get all judgmental.
Should Tesla contact all their reservation holders every time they make a change to how the car is made? Every time a part is changed? What if they start using a different LED bulb in the overhead lighting? What if they start using a different Velcro to hold down the mats. What if they change the thread in the seats that they are sewing? What about if they change the color of the foam in their seats? How about change the molding of a plastic part, such that it comes out of the mold easier?
Tesla can't tell you about all the changes they make. Sure something as visible as a headliner will be noticed. And perhaps should have been communicated.
But what if they stopped using the Alcantara headliner for another reason. Perhaps their supplier told them the price was going up, and their commitment was over with. Perhaps the supplier was having problems making the headliners and told Tesla they wouldn't make them any more. Maybe there were quality issues with the headliners and Tesla decided they didn't meet a quality requirement. Perhaps they saw some issues with premature wear of the headliners, and they started to sag. And Tesla decided having a 'cheap' headliner would be better than having a droopy headliner. Maybe the Alcantara was shedding and getting small microfibers all over the dash and screens, and Tesla decided it wasn't acceptable.
Maybe Tesla made the car HIGHER (by some other non-aesthetic measure) quality by removing the headliner?
Also I have never seen any writing that says that you will get an Alcantara headliner. And I don't think anyone else on the forum is claiming to see such language. I would hardly call a headliner an 'accent' piece.
A lot of this problem is coming from Tesla's sales model. You order, and get what you get. Versus you looking on a lot, and getting what you touched. I know that buying something online is different than buying something at the store. I accept some of the risks. I will NEVER buy shoes online for this reason. I have bought one pair of shoes online in the past decade, because I couldn't find a store in Atlanta that sold the boots I was looking for. They were exactly the same as my previous work steel toe boots. But they weren't. The laces were different, and much crappier. The eyelets were different, can't really tell if they were better/worse but they were different. And well the tongue was sewn all messed up in my left boot. It still won't stay behind the laces after over 1 year of wear. Part of the deal with buying online. I won't do it again, because I am VERY particular about my shoes. I am not so much with my car.