Okay, think of it this way, blizzard is doing this system revamp to allow players to get a feel for their builds before they get to level 40/50 when most of these spec defining talents and abilities first become available in the current system. "Now I put my first talent point into Subtlety and WOOT, my Ambushes and Backstabs are ZOMGAWESOME. I am happy, put my backstab onto my toolbar and run up to my first mob after levelling, go stealth and Ambush, woot, awesome it crit, now I backstab.... I said backstab... wtf, stop turning towards me you stupid mob, I want to backstab, zomg, ack, sinister strike, sinister strike, why is my sinister strike so weak? Shit, I sold my sword after learning my dagger was leet, damn... I'm dead. Okay, this spec sucks, I'm gonna respec... wtf? I don't have that much money!? I'm stuck this way now? Forget this, I quit." Backstab isn't exactly a solo-friendly ability, so I see Subtlety providing some 1H perks along with the dagger perks. Dagger may pull ahead marginally especially if you are proficient at staying in the rear arc of a target, but for the sake of the solo levelling experience, unless they remove the positional requirement from backstab, I think Subtlety will remain a Dagger and 1H friendly tree.
Also, during Wrath, Subtlety was more of a "Weapon Swap to 1h when you aren't using Ambush" type of tree until the hemo change.