The problem is that it takes a lot of computer power needed to run an EV. Battery management, power management, motor control, etc. Requiring that much computer power makes it a cheap and easy decision for car makers to just make everything part of that system.
We will get there eventually but it’s going to take a lot of people to want it (many people aren’t even considering an EV as a future car purchase), a lot of the under-the-hood stuff will have to be shoved away, and charging/battery management need to be simplified while still being robust and reliable. I don’t see it happening any time soon, ICE vehicles have only been getting more and more complex in this way. “Stick a tablet in there” is so cheap and easy and resolves so many manufacturing hurdles.
Bespoke windows controls? Nah, button on a screen. Custom entertainment system? App on a tablet. Backup camera screen? Just put in on the screen so it’s the only thing you can see while backing up.
If car makers cant get around these hurdles without incurring, previously saved, costs, the trend will continue.