Many of the devices in cars currently have bugs, poor interface, slow performance, and are generally inferior to modern phones. So, continuing to perform as they do now is not a relief.
It’s like having a phone from 2014 built into ... uh, your car. I’ve upgraded my real phones and tablets 3-4 times since then, despite that the old ones still functioned same as they did when new.
One example is that it’s difficult to pair iPhones with some cars from a few years ago. What happens when software updates make me unable to connect to the Bluetooth in my car? I doubt that Ford or GM is going to release a timely update.
You might ask: why do people upgrade computing devices that still function?