Comment 8 for bug 48734

I'm afraid we'll have to agree to disagree on this one. I firmly believe
that if people have to opt in to being able to share files with each
other then they simply won't do it, or will use absurd,
expensive-for-the-Internet workarounds (like e-mailing files to each
other). Most people don't lock their desks up by default either, only if
they have a clear reason to do so. The knob is there for people to tweak
and I honestly am not interested in discussing it beyond that at the
level of the installer. I recommend opening a separate bug to make it
easier to configure this sort of thing at the desktop level.

Somebody should probably also open a separate bug to have the apparmor
configuration for the guest session a bit stricter.