The language in the description of Torment specifies "New legendary recipes can drop in this difficulty" and "New legendary items can drop in this difficulty." Your magic find is increased, but I think that there are also items that can only drop in Torment difficulty.
Additionally, I've noticed that I get some rare drops that have roll chances up to 329 on some primary stats while playing Torment. It seemed like all the rare drops I saw in the difficulties prior to Torment peaked at about 219. Or was it 249? In any case it was lower. This could just be "chance" and my observation was based on the higher magic find and other-than-that nothing to do with being on Torment. Not sure.
You're right. There are definitely items that only drop in Torment. This I know for sure. However, I could have sworn I read that the difficulty doesn't affect item quality, but you may be right. I certainly have played enough to know for sure one way or the other. It would be nice if Blizzard gave us a direct answer to this though.
I played some more last night on a new Barb, and I'm having fun with it. I found this guy in Act I around level 22. The proc rate is high enough that with Frenzy the champion is almost always up. No idea how much he helps though. It's a fun affect none the less.