For starters, most definitely not "everyone" is playing Ret, especially in Arena. While 2.3 buffed Ret somewhat, they are still rather easy to counter in Arena. And frankly, I did not even know there was such a thing as "the Ret Arena spec", since most Pallies in Arena will be Holy and all that.
Now, as for the actual question... Let's see the old talents you said you used to take to improve the stuff you usually use.
BoMight: I think Kings is better for Arena for the added survivability, if available. But I know this is usually left to the player's preference.
Sanc Aura: The normal aura is good for you, but the improved version is really of minor use in Arena. 2% damage will not change much in what should be rather short fights. (It's probably more suited for PvE in that respect)
SoC: Well, of course.
Healing: Usually a waste. You should have no +Heal whatsoever on you gear, so your heals are as strong as a healer trying to melee or something. Basically you'll burn all your mana trying to keep someone alive. (Which won't work most of the time if he's being focused)
As for what you said changed...
Devo Aura: I've never really liked it, but I guess it can make your squishies that much less squishy. I guess it'd depend on the situation. It's just that you have zero use for Redoubt anyway since you don't have a shield, so that makes Imp Devo Aura the default choice to progress further in the tree.
The rest of the investments in Prot are for more survivability and a little bit more utility. (BoP more often, stun more often, avoid stuns, miss less, etc)
Vindication: This used to be 15% less Str and Agi, but it is now all stats, so it can significantly lower your enemies' stats. Too bad it's a magic debuff and can be dispelled. Better than nothing I guess and it can waste a healer's GCD on dispelling it. (Or group with a Lock who puts UA on people so no one tries to dispel it)
PoJ: It has finally been changed to make you run faster than people with the minor speed enchant to boots. Not a huge difference, but that's pretty much all you can do for your mobility, which as a Ret Pally you lack a lot.
All that being said, I can't really tell which spec is bad and which is good.