I think the main reason it stings is that these changes are launched with seemingly arbitrary timing and no semi-reliable advance notice (though this particular announcement happening the day before earnings is unlikely to be a coincidence), so it's impossible to make an informed decision, and there's no consolation to those who picked a bad time to buy.
So they should tell you they are about to release a new model with better range, better suspension, etc. to inform your buying decision? You would then not buy the current model for sure, which they need to unload or then mark down huge amount in fire sale which hurts revenues.
This is the way Tesla has always operated and should not be a surprise to anyone and you should understand why they do that. I note they are the only car company that will improve your car at no extra cost while it sits in your garage too. So is it really valid to complain?
I bought a 2018 Model X right at end of the year. I would surely like the new one better, but I really like this car and I paid for FSD, which if it comes to pass will make this an even greater buy.