You would have to be really unlucky to find the right conditions for rollback in winter, and in any case all the engines should have been modded a couple of years ago.
Also, rollback is not necessarily an engine failure per se, it is a rising TGT and decaying RPM that MAY, if not recognised, lead to a pilot-induced shutdown of the engine. Well, I suppose the thing would fail eventually...
The importance of that is that you don't necessarily lose all your services (hydraulics and generators).
The point about the Aussie case was also that it was mis-handled by the crew.