In any event, as you say yourself, the steeper curve allows more precision in determining the state of charge, not less.
But that was not the issue you were bringing up. You complained of the amount of energy changing very quickly when left to sit and settle. And that is exactly what it does when it is in that part of the line with the voltage change being very steep.
It's hard to accelerate at all when the battery surprises you with 0% state of charge.
Well, not really. As some people have pointed out, Tesla seems to have re-instituted the "below 0 buffer", where the car will usually have a bit left when the meter gets to displaying 0%.
You need to read the thread in context. "They were having to combat this weird false myth about electric cars that if they were left plugged in when they got "full", that the connection would continue to force feed electricity into it until they exploded!"
Now does the statement make sense?
I just reread it, in context, and yes, it absolutely makes perfect sense. This is what you said:
There are recommendations to keep the car plugged in at all times, no?
When you are driving the car, it obviously can't be plugged in. Sitting in a parking lot, it will frequently not be plugged in. The cars can sit for several days at a time without being plugged in, and they do not suffer harm from that either. "at all times" is definitely an exaggeration and not really what Tesla recommends exactly. But I was explaining why Tesla would give a recommendation similar to that about keeping the car plugged in excessively more than it needs. And having to fight that wives' tale misinformation about remaining plugged in leading to overcharging and exploding is one of the reasons they needed to say that, which was not related to idle drain energy consumption. So you brought it up, and I explained multiple reasons of why they published that type of recommendation. That was just one of them.
That would be great, but Tesla doesn't tell you exactly how to use the car or how to best maintain the battery.
Yes they do! As much as is really needed. It's the simplest way to get the best balance of most benefit for the most amount of people for the most use cases.
However, they are selling a consumer product. If they were to give excessive detail with many pages of steps and charts of various conditions and how to do things several ways to be the most perfect, it would have two negative consequences:
1. It would be problematic for some people's use cases, where they need to use their cars outside of what is the most "ideal" treatment of the battery. And then that would mount up to lots of calls and service visits with people trying to reconcile that contradiction between needing a car they can use but being concerned with violating these recommendations and conditions.
2. It would feed the FUD of the haters and the fears of those who just don't know but are scared and worried about new technology they don't understand that well. If it has complicated steps and conditions they have to remember, that will seem overwhelming and discourage them from considering buying an electric car. And they would continue spreading these negative rumors about how electric cars are too scary and complicated to use.
So for those reasons, Tesla doesn't want to go too over-the-top with making it complicated. They keep it pretty simple, with the 50% to 90% being OK for constant daily use, and above 90% being OK for occasional use. Simple. Don't worry people. If you park with a very low state of charge, it will display a simple message saying you should probably plug in. If you charge it up really full several times, it will also display a simple message saying it's not a good idea to do that a lot. Also simple.
There are many issues that require significant research on your own.
No. That is not required. If people never look any of that up or do that research, THEY WILL STILL BE FINE. It is not required to obsess like that.
I recall advice that the battery should never be charged to 100% for maximum battery life, then Musk says it's perfectly ok to charge to 100% when you need as long as it's "not too much". The only way a user can make sense of this is to be given some reasonable way to valuate the impact. Being told "it's ok to do sometimes" doesn't tell me diddly squat really.
As I just mentioned above, people don't need to look this up or worry about it. The car will give a simple message guiding you. It's fine. And really, this kind of seems like you're not being serious here. Plenty of things in life are known to be bad to do excessively or constantly--eating junk food, excessive alcohol, smoking, revving your car to redline, speeding. People moderate things all the time in their lives without having to know an exact quantified number of what the impact will be of doing it too much. "This generally isn't good; I shouldn't do it all the time."
Maybe you know about the temperature profile and how the state of charge is impacted at what temperatures? In particular I'm concerned about parking after a couple hours of driving with some amount of charge on the car and finding a very low remaining charge when I return a week later and the weather is now around 10 °F. At what point does the car heat the battery to prevent damage? Is there any data on how much the state of charge is impacted when cooled from operating temperature to an ambient of 10 °F as a function of the starting state of charge? I've not seen this in the manual. It creates anxiety for me.
I am sorry that you have so much anxiety about this, and I am trying my best to let you know that you DON'T need to obsess and worry about this so much. They designed these with extremely detailed systems to prevent people from being able to accidentally destroy them. It's the public--they know what the public is like. I wouldn't recommend what you are suggesting, of parking the car in the cold with a very low state of charge and then leaving it that way for a week. It's not that it's going to destroy the main battery, but just because you will probably cause yourself a lot of inconvenience.
If the car is really running low and can't get recharged, it will just keep the main pack disconnected, with a safety buffer of energy left in there (that you are never allowed to access) so that the battery will not be drained completely and harmed too much. The idle systems in the car will eventually drain the little 12V battery, so you will have to get service or a tow truck or something to deal with that hassle and maybe have to replace that 12V, but you can get it somewhere and get it charging, and it will be OK.