I don't think it is a bad idea unless they have some secret sauce that nobody else know, which if you hack would be IP theft.
If the engine / motor / battery can handle it then there will be ways to get there with aftermarket mod instead of hack to unlock. If it is because doing so will cause more damage so OEM need extra money to pay for the higher warranty cost then you can say it is a trade off between voiding warranty vs getting official warranty to do something.
It is actually not hard to hack things, or bypass things, if the way to achieve it is a complete reverse engineering or aftermarket solution (voiding warranty, "track use only") that engineering companies have been doing for a long time. It is just a matter of "is it cheaper to just pay $1200 a year" to get it out of the system, or spend $30000 to get a reverse engineered system in the to replace what you already have.
Now the heated seat subscription is just dumb, You can pretty much modify a $20 smart home switch to bypass nonsense like this and I'm sure somebody would print some circuit board and sell these on eBay from China for $30 each and then you can use your smart phone app to turn on and off instead of paying BMW every year.