The user interface of version 7 and below were the best. Modern UIs like in version 9 look like it was made by lazy designers. The good thing about version 8 is that it uses radar for Autopilot, the interface was not as flat and bad as in version 9 (it still had 3D icons), and it still had the ability to choose any 2 apps.
I don't know if the designers were lazy, but instead, time challenged. I think one of the things we, Tesla owners, are proud of, is over-the-air software/firmware updates. It's one of the first thing every Tesla owner cites as an advantage/feature of Teslas.
I think what really happened is that Musk, with truely good intentions, says/tweets how great the next version of auto-pilot and the user interface will be, and then AP just drags on and on while sales are flat and the stock just stews, because we all want the next new shiny thing.
Then the UI people are forced to create new eye candy for us with just weeks to "throw" it together to keep eyeballs positively on Tesla. The sad part is that Elon, needs to be more like Steve Jobs, and just say "no, it's sh#t. Fix it." Instead he green lights sh#t to hopefully keep the cars selling and stock up.
There really can't be anyone in Tesla that thinks they have improved functionality. Sure, clean up the icons, tighten things here and there, but keep some depth and contrast for legibility. To me real functionality would have been being able to have user defined skins/preferences so that I could have larger font sizes, onscreen user buttons to execute additional user presets, etc.
Who wouldn't want a button that changes the mirrors from looking at the blind spots to looking back down the side of the car for motorcycles changing lanes, etc. Heck, tie it to a script that says when in Auto pilot, change mirror setting. That's when I really want it. Then again, shouldn't AP be looking for lane splitters and helping them out by moving over a bit?