Perhaps you're right with the description thing, or maybe the rate at the game has developed means the description is no longer accurate. It's not too important compared to things like balance and actual gameplay issues, but made me chuckle how wrong it was none-the-less.
To be quite honest if we treat arms as a Blademaster, master of weapons and all that then it may even make more sense for arms to get some form of ArP. I wouldn't like to throw ideas around because with the resetting of CS it kinda already has a form of ArP which has a fairly high uptime, especially if we're lucky with procs. In my personal opinion Opportunist Strike is hella derpy and just feels like a copy and paste from Rogues... Which I wouldn't at all be surprised at.
On the subject of Fury Mastery, I do see your point where once we reach 100% mastery we'd be doing our maximum damage, but that's probably a similar issue to Elemental where they're reaching 100% mastery and going more into haste or even just pure intellect. I think it would be the biggest "overhaul" Fury would need/get (not really need but benefit from) without the class being stripped of all recognition. I do like the idea of the CS window and everything revolving around it being the difference between good and bad Fury Warriors but at the same time it kinda loses it's "raw" feeling. I dunno...
Regardless I look forward to WoD, the level 100 talents look/feel a bit lackluster and quite frankly they seem copy and pasted from a Diablo 3 Barbarian but it's early days still, subject to change and all that. Perhaps Blade Barrier or Ravager will be the abilities we need to include more passive cleave? I wouldn't be at all surprised if TG with glyphed WW becomes manditory (the one raging blow one, can't recall it's name) for that bit of cleave.