Move all your developers to stability for two years.
After countless posts in here about stability, it's still bad and still getting worse.
Here's my suggestion, it's very actionable: Move every single person on the Premiere team to stability and stop work on everything else.
I should never have a sequence that's rendered and still won't play back. I shouldn't have to restart my computer regularly because simply closing a project freezes premiere so hard that it won't force quit (usually hard restart because I can't even force quit). Similarly, it shouldn't crash and then not be able to open again until I restart.
Sure there's lots of other improvements to be made, but if Premiere can't even play back simple video reliably or open and close properly, you have zero reason to work on anything else.