why does NetworkManager: "taking down device" on exit?

[Marc Herbert <Marc Herbert gmail com>]

I am using NM 0.7.1, sorry if this has changed or already been discussed.

Why does NM force all links down when exiting? Does this serve any
purpose?  This kills basic IPv6 connectivity, something NM is not needed
for. Actually, this kills any other (less common) protocol you can think of.

Note that this problem does not happen when NM times out a DHCP attempt.
In this case the link is only "deactivated" and stays up.

It is quite counter-intuitive that it is easier to co-exist with NM alive
than dead.