A complete new Development of the WorldEditor would bring the
most advance in Workflow.
WED is a patchworked program based on an old Editor from 1999.

I dont see why there was no Engine-based Rendering implemented long
time ago into WED.
The whole purpose of GED is to make some workaround for
functionalities that should have been in WED long ago.

Also the Level-format should be based on something like xml
or other plaintext format (at least as optional saveformat)
So usermade Editors or script-processors can interchange with
the levelformat, and add custom functionalities.

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The other big issue is the multiplayer part.
There should be at least a more advanced reference implementation made available.
And the silly limits to playernumber and dedicated servers removed.
(There is plenty room for Pro-exclusive extras in other areas)