Bassman2003
Veteran
EF became popular because so many people own Canon lenses, not because it is such a great mount. It is just a lens mount. Getting everybody to band together and make a unified mount would be like herding cats. 
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Well, PL is great, but I'd hardly call it universal. You can put basically any lens on a m43 or E mount (including PL), but PL mount only takes PL lenses.
If they let me decide that new universal mount, it would sound as follows:
Then you can make your universal-plate-to-whatever-mount adapter. There would be $30 aluminium dumb adapters, and $1000 titanium ones with electronics and whatnot.
PL is universal enough for the movie industry. All the best glass is available in PL.
You completely missed the point of using a sub mount underneath. How many potential buyers of low end cheap cinema cameras (such as from BMD and Kinefinity) can not shoot 100% of their projects exclusively with PL lenses?? Many many many many of them!
Exactly! I was just mentioning one reason, but there are many other reasons why having an adaptable sub mount is beneficial.