In my previous post I was complaining a bit about the loot drops in Diablo 3 - my thoughts were that why should you play at torment levels when legendary drops still happen at Normal difficulty. Well, it appears that while legendaries do indeed drop at the pre-torment difficulties, there are certain items that can only drop when your difficulty is set to Torment 2 and above (I might be wrong about the 2 part, but yes).
After doing some research, I saw that there are some really cool gear items that you can find when you push the difficulty up to Torment 2 and above! For example, there are legendary potions, and class specific set items!
Here are some links that I found handy
It appears that certain acts also have specific drops from the Horadric caches that you get for completing bounties, with the exception of Act 4, where any of the Act-specific items can drop from the cache.
Also, with my Level 70 Demon Hunter I have actually gotten a piece of the Natalya's Vengeance set already, didn't realise that it was because I was playing on Torment :)
So, if you want the good gear, go ahead and play at least on Torment 2 ;) I did a rift run last night with my Witch Doctor, and the boss dropped a very nice legendary ring. It did take a while to finish it though, a good hour or so!