You could make the same argument about houses - imagine how much cheaper it would be if every house was built out of prefabricates, but you just had to pay extra to get the additional rooms! What arrives from the house factory has 2 bathrooms, but one is sealed shut unless you pay the fee! But that's all fine, as long as the customer can save some money?
We can already see what happens with this approach taken to the extreme - look at BMW and CarPlay. Instead of selling it as an add-on from factory for say $300, you can pay yearly to have it - about $50. And BMW says "this is great, it's saving the customers money! Average car owner has the car for 3-4 years, so they will pay less in the yearly subscription than they would have done in a one-off fee! Isn't that great for everyone?". That's nuts. Absolutely positively nuts. To extend that to heated seats - I can easily imagine some company making those things available as a pay-pass, where you pay say $0.99 to have the seats available for a day. Again, someone will say "that's fantastic! It's cheaper than paying for those seats as an option from factory, if you don't need them you don't actually pay anything!". It's absolute madness and we're encouraging this.