I have Skinning/Herb. Never really cared about the crafting professions.. I read that it would be foolish to not have a crafting profession going into Legion because of the gear you can get.. Why? Wouldn't I just earn lots of money from my skinning and herbing that I can just buy off the AH?
You don't need crafting professions at all if all you want is gear for yourself. Just buy 815 pieces for the slots you want and use the Blood of Sargeras you get from gathering to apply Obliterum to your gear. There will be a time however where you have all your gear upgraded and you keep getting Blood of Sargeras which means you can't convert those Blood of Sargeras to gold. But that might change in the future.