All skills also need to be balanced for PvP. This is true for arena and also for the story (at some points you can brawl each other, theoretically you can leave your party at any point and backstab everything, if you want to).
Taunt is really really good in PvP. At least it was for me. I guess that piercing armour would be silly, since it is almost a hard CC.
Regarding PvE, well if there is no physical armour, I just cripple or knock down them. I guess that is why so many complain.
