Tank dps is fine. The reason tank dps appears low is, because your your gear is bad. You also may be comparing yourself to a dps which has several dps cooldowns. The only reasons tanks do nice dmg in some other games (you're probably thinking vengeance in wow) is, because tanks weren't able to hold threat well before then,because dmg was outscaling there threat modifiers and blizzard took the easy way out. So no tanks are fine if you want big dmg play a dps if you want to be the last line of defense between your team and death play tank.