I definitely suggest EVERYONE escalate this issue via your Tesla account. This will not be fixed by staying quiet or avoiding the update. Especially since eventually your car will break something that requires an update to replace like a drive unit for example.
To submit a concern for executive review, log into your Tesla account on the Tesla website, select manage your vehicle and under support select escalate your concern for executive review and submit your concerns. In this case reduced function of 9.0 and not being able to use the top portion of the display anymore vs 8.1 version of the in car software.
Heres what I sent
"Hello,
I have an issue with the new 9.0 software. I like to keep the rear view camera or the web browser on the top half of my screen when driving. It seems like this is no longer allowed with v9.0. I can’t seem to get anything but the map on the top portion of the screen. You have decreased the functionality of the 17 inch screen to only allow one user selected app to be displayed on the bottom of the display!? To top that off I RARELY use the in car maps on the main center display for more then a few moments especially since once I’ve entered a destination it displays turn by turn directions on the dashboard behind the steering wheel. At that point I switch the center display to rearview camera or web browser with WAZE. Please restore the ability to choose what applications I display on the top of my center console!
You should not be taking features away from customers, if anything we should have more user interface freedom, not less! For example how about letting us choose where things are displayed etc just like with a phone where you can move your most used applications around as well. "