@Rob yeah sounds like it could be a good idea, one thing I'd suggest is maybe having the GM adding the tokens to a player library, possibly along the lines of:
>Click on "Art Library" tab
>Click Player Library icon (ideally either a button or an icon next to the "my art library" star icon
{opens a new window}
> Drag n Drop asset from art library search into Player Library
Players could open their library from... somewhere - settings tab? Journal tab? Button on toolbar, maybe?
To stop players taking *ahem* liberties by spamming the area with tokens, there could be an option somewhere (in the player library window itself would be my suggestion) which says which players have access to the library, similar to the journal and token control. Each player in the list can place and control those tokens (automatically adds "controlled" permissions to tokens when placed?), players not in the list cannot.
*thinking out loud*
Would removing "Richard Head" from the list make him unable to control any tokens already on the table or just not able to add any more tokens? I suppose you could just remove his name from existing tokens...
*/thinking out loud*
But that's how I'd sorta envision it working.
If it is doable, or if it is worth doing, is another question for Riley And All His Little Wizards (sorry, too much Blackadder II recently) to decide.