A specific restriction from operating in freezing rain was removed from our GOM a few revisions back. I was told the thought process was that since flight in freezing rain is prohibited by regulation (no flight in severe icing conditions) it was already covered and didn't need to be specifically addressed. Now we're debating freezing drizzle. Fortunately, the AFM for the aircraft I fly has a specific limitation against flying in freezing rain OR freezing drizzle. Done deal.