I get it if they are modifying it to remove something you paid for, but that is NOT the case here.
Absolutely yes. The problem is they are accessing and modifying something that they do not legally own (IANAL --- but the terminology they use when referring to paying and then being able to use a vehicle they made sounds very much not a rental or a lease), regardless of what that modification is.
To stretch the analogy, I would be just as pissed if GM decided to send someone to my house and replace the tires on my car with new ones, and I couldn't do anything to stop them.
Furthermore, the whole VW emissions thing shows what real ownership means --- they came up with an update to reduce emissions (and likely power or fuel economy...), and probably very strongly encouraged owners to get it, but ultimately if someone bought the car then they can't just go and "fix" it, even if they were found to be violating emissions laws, because they still need consent from the owner.
In Tesla's case, it sounds like the owner has no ability to say no.
Regardless, I find it very hard to believe that an update to remove features Tesla believes it hasn't been paid for will be anything but non-consensual.
Also look at my UPDATE post. It looks like this is 100% consensual. As I expected the people who were effected by this knew when they accepted delivery of the car that these features were a sort of free trial. They could have declined the car and waited until the the features were locked out but they accepted it knowing they were a free trial.
Model 3 updates are opt in.
In this narrow case though the ability to say no was at the time of contract signing and it was made super clear up front (i.e. not in fine print) what was going to happen.
The people affected by this update accepted it when they bought their car and were told they would be receiving these features temporarily for free, and were told they would be removed when the software was ready.
(Most customers of consumer electronics products have the same relationship with the makers thereof, and that's a big part of why practically everything with a screen is on some level regarded as disposable garbage.)
On the other hand, if you drive around in an old Honda like I do, the worst thing Honda can do to me is stop manufacturing replacement parts, most of which probably have third-party alternatives anyways.
"Sorry, but you only paid for 15mpg from your BMW".
Also I probably should point out that when the updates come out it is still up to the user, at least to some extent on whether they want to upgrade or not. I think it turns into a snooze game though but I know there were people that held out for years on software updates because they liked the old UX better. So you don't HAVE to update, its just pretty much universally preferred to upgrade.