Who says Replenishment was just for healers? It was meant for all mana users.

And also, gear inflation in Wrath was ridiculous but that won't happen in Cataclysm since 10 and 25-man will share loot tables.

As a person with a shaman whose off-set was ilevel 200-219 gear mostly, I can tell you gear inflation was unimportant. Shaman in Ulduar 25 gear didn't care about mana anymore.

I don't think they'll be able to balance vengeance. You have to balance a bunch of skills around it or they are too good with it. So that WoG that is utterly pathetic when you are not the main tank? It's okay as a main tank. Otherwise it is beyond OP as the main tank.
That design principle never works.

"making all the plate tanks gain DPS (ie threat) stats from tanking gear"

Tanking gear has increased stamina.
Stamina gives you more HP.
If you have more HP you get more AP from vengeance.
AP is a DPS (ie threat) stat.

Bears don't wear plate.

"Want tanks to not be beat in threat? Have them have... a system where being attacked makes them do more damage in PVE only."

You mean like vengeance?

Scher: vengeance is a DPS monster.
It doesn't give you threat stats from armor, it gives you a stupidly large AP boost.
When a tank is outdoing the pure classes for DPS because he is eating damage a lot, it is a broken system.
When you HAD a way to may a tank's stuff scale with their stats but now you have to change those things because if they have vengeance stacked they can alter how the fight works with self healing, damage absorbing or some other mechanic it isn't scaling.

Bears already get threat stats on their gear. Wearing rogue leather isn't a problem for them.
They get more rage from crits and haste so with some tweaks they could be easily made to do comparable to plate tanks for this.

Finally, vengeance works in PVP and they made it ramp up like that partially to avoid it being too good in PVP. So no, not like vengeance. The ability needs to be locked out of organized PVP so it can work well and not get a massive nerf from the QQ that would happen.

A stupidly large AP boost is a threat stat (from your armor!). Vengeance is meant to make tank threat scale off tank oriented gear, hopefully as well as dps threat scales off dps oriented gear. What people seem to be saying is that it's currently working too well (too much extra damage/threat).

If what you're saying about bears was true, in late WotLK bears would have either a) been the preferred tank as their threat would've gone much higher than plate tanks & in turn allowed higher dps & shorter fights; or b) been completely forgotten about as their survivability would've lagged behind due to all the "threat stats" on their gear.

I agree with your point that vengeance has been designed not to be good in PvP. Everything you said you wanted in your original post (threat stats from tank gear, pve only damage boost) is exactly what vengeance already is.

Maybe the solution is to have vengeance give the same +threat bonus to each attack it already gives now, without actually dealing any extra damage.

Um... Since when was a decent tank beating a decent Damage Dealer's DPS? From what I see, I'm still nearly at the bottom of the DPS chart, and I still don't have issues in holding threat...

I think you're just paranoid.

My entire point on this is that vengeance is a hammer.
It isn't precise, it doesn't really scale correctly.

So what has happened is that bears have had their armor dodge and health dramatically altered to not make it too good for them, avoidance stats are discouraged, and tools the tanks had that would have scaled with AP are now too good with vengeance.

And they keep hammering at it instead of looking for a good alternative.
They did this with replenishment. Instead of just getting rid of it because it was too good they kept trying to balance all the classes around it, and it wasn't working.

A hammer is great at doing one thing. Vengeance will be the same, it will be great at one thing. The problem is, tanks have other tools and vengeance is going to break them because they need other kinds of tools and the devs applied a hammer to them.
WoG has been hit hard. Without Vengeance propping it up, it is a waste of a GCD. I have seen this first hand. Shor/Shield Bash, savage defense, etc... they all were designed to scale off of gear so the more AP you had, the better they were. Vengeance added to the mix completely threw them out of synch.

The tool itself has a major issue in that once you build a threat lead, there is no worrying about threat at all. No one will creep up, ever. Because at max stacks it makes your TPS way beyond what it needs to be. You can go afk and not care at that point. It isn't precise, it isn't doing what they want, it is screwing up other abilities. They got tons of feedback saying precisely this in the beta and they stuck to their guns instead of backing off and saying "well, it couldn't be balanced, it gets to sit next to spirit link and wait in the corner until we can get it right"