And in the winter, I'd love to be able to warm the engine and the interior from inside my house while I gather my things for work.
This is clearly a case of prioritising convenience over security, which you're welcome to do as your own personal preference but I would never choose myself.
This data is used to help triage the severity of the crash before the EMTs roll out.
Well that's probably the single most disturbing thing I've seen in this whole discussion. Are you really telling me that in the event of a known road traffic accident, which is severe enough that no-one on the scene can immediately respond to verbal contact, they don't routinely send the full works where you are?
In any case, I would point out that this is purely status reporting, i.e., read-only data. There is no need for anyone to control anything remotely in this situation.
Also, in extreme cases, the OnStar / Bluelink / et al. system can actively end a felon's joyride by cutting throttle, braking, or cutting the engine entirely. Then it can honk and flash the lights to attract the authorities' attention.
This is my main problem with the whole debate: any system that can do this kind of thing can also be used for less welcome purposes.
Car theft is essentially a solved problem without any remote control needed. Technologies like immobilisers have become so good that stealing the car keys has been the preferred technique for some time. Trackers, which need no integration with any control system, provide an effective deterrent and means for police to locate a vehicle that has literally been put on the back of a lorry.
Again, YMMV, but personally I would rather be careful about where I keep my keys than risk a hostile party, or simply a human error or software bug, doing something like cutting the engine and applying the brakes when I'm driving at high speed or through a hazardous area.