Tesla has done this for a long while. Newer larger battery pack options, newer interior and tech package options, and completely new performance and configuration options (insane, dual motor, and autopilot 1.0 all hit at once)
While there wern't announcements ahead of time what was coming, there were often advance notice that there was an announcement coming, and even when there wasn't - there was a big period of quiet from Tesla leading up to it.
For Autopilot 2.0 everyone knew it was coming for at least the Model 3 launch (Elon said as much at the Model 3 announcement), they just brought it forward.
It is really no different to what happens to customers for a bunch of other tech companies. Canon sure doesn't tell anyone when their new models are coming out - you know it'll probably happen at a major trade show, but only if you're someone that follows that kind of thing. The average customer at their camera shop isn't going to have the sales guy say "Hey, wait a week and we'll have the next version available."
Regardless, I think it’s a fair critique: buyer’s remorse is a real thing with Tesla. It’s one thing to buy a $3000 computer from Apple and have it replaced with a much better one the next week, it’s another to buy a $100K car and have a major improvement two weeks later.
Plus people but cars when then want cars, some will always lament they could have waited a bit, but most I expect will be happy to own a Tesla that was (and is) amazing just a few days ago.
If you want change in this regard, it's not going to come from Tesla.
For instance, let's say I pre-ordered a Model 3 now. But I won't get it the first half of 2019. And then a month later, Tesla announces Model 3 with Autopilot 2.5 hardware or whatever, holographic HUD, and so on. And that new car will ship within 2 months. Then I'd feel pretty screwed by Tesla...
In short, the delay between reservation and receiving the car is not an issue.
Big difference between buying a camera and buying a car.
For a young professional, buying a $35k car is probably just as eventful and significant to their savings/expenditure.
vs. "Hey, we have this great sale going on. What, new model? Naww, we are just having a sale!!"
The incumbent MFG's literally have "new inventory" sales on their last-years model to clear out inventory. They let you know well in advance that a new car is coming with new features so you can make an informed decision.
Is this not what "hey this 1-2 year old model is on super duper sale right now, it's really cheap, you should buy it!" means? Is a steep discount on older stock not always code for "better shift these before new model comes out"?
You see Apple fanboys fall for this one every time, too. "Yay I got a new iPhone 5 last week and it was SO CHEAP, I'm a genius... wait wtf they just announced the iPhone 6."
The upstart, by virtue of simply not yet having that many potential repeat customers around, is targeting first time buyers. The goodwill created by having as little obsolescence as possible far outweighs the extra sales they might get through it. This tradeoff changes significantly once a company is established and the number of potential repeat customers is high. Now it's always a balance between repeat sale likelihood and repeat sale cycle duration.
Different forms of obsolescence have different effects in different markets. E.g. unlike smartphone makers, car manufacturers tread very carefully when it comes to longevity. Red book value and all that. So what do they do? They have perfected the generational model update cycle. New generation cars are literally designed to make the predecessor look old, because that is the most acceptable repeat sale driver. Tesla just isn't there yet.
edit: I'm absolutely positive I'm missing the joke here
It's tough because if you are custom ordering a car mid-year there's a question as to whether to wait for a production allocation in the new model year or not.