Its interesting to think about if resist and pierce keep going up. I mean even if someone has 130% resist and a 70% shield, an opponent with 150% pierce will go straight through the shield and still have 80% pierce left to reduce resist to 50%. There are plenty of options for pierce including gear, globals, auras, shrike, pet talents, jewels, blades, etc.
I think as long as pierce continues to increase more than resist then it could even be more balanced and make jade gear obsolete - the problem is the lv60ish players where jade gear is very effective and there aren't as many pierce options available (no shrike, less gear, less jewels etc).
In theory, having 150% pierce and 130% resist would make sense against a 70% shield, you're right, but that's only if there's a shield on the player getting attacked. If there isn't a shield, then attacks will be going through on 0% resist, meaning attacks would deal absolutely ridiculous amounts of damage. And you already know how much damage people can do when they have Shrike up.
I believe that armor pierce resist is the only solution to rebalancing damage, resist, and armor pierce together again.
