I suppose it's a similar argument as answering the question "why shouldn't sicker people pay way higher insurance premiums instead of driving up the average cost". For health insurance I think the pool of insured people to protect against black swan type problems is reasonable and ethical (it protects people with birth defects etc.). However for car insurances I feel like this argument doesn't hold as your driving behavior is very much in your control.

The interesting question is if it might actually be a smart strategic move to announce such a use of data. It's a bit counterintuitive as that would limit your customer pool. However I think there are benefits to limiting your customer pool to more "positive" cases. Let's say Tesla would announce that they'd collect data on reckless driving, warn the drivers and upon ignoring the warnings a couple of times inform insurers about it. That would probably result in less reckless drivers buying their cars which might actually not be horrible since that would also reduce the number of accidents etc. The big issue is of course that it would violate all reasonable privacy laws I can think of (I guess they could make it opt in).

[all assuming non-automated driving]