Inability to restrict Places is a security issue

In an education environment (like with a kiosk), certain users cannot be allowed unfettered access to the file system. Exposing the filesystem in the Places menu or explorer navigator or on the desktop, is an invitation to click - mount - and cause general mayhem for an unwitting pre-school child. Originally I was keen to use Unity but I couldn't get account based restrictions on the content of the launchers (the requirement was much the same), so I switched to Gnome, where the menu policy editor does at least a partial job at restricting the applications available. The remaining issue is the lack of provision to turn off visibility of the disk partitions (&c.?) All I want in Places, whether via the menu or the left column of the explorer or on the desktop are visible folders in the kid's account directory.

After some Googling, it seems this is a) impossible and b) a popular requirement. To me it seems like a fairly trivial exercise for the development team to knock out and it would open up all those applications where this use case is of primary importance!

My questions are:
Is this recognised as a requirement? (control of fine grain access policy, esp 'Places')
If yes, then what's its priority?
If no, then please justify why not?
If you're not sure, please have a think about the use case and explain how it isn't a critical requirement for such usage?

Cheers,

Greg