im all for adding a new Tank and healer
i was one of those who wanted to try tanking with Dark knight and learned to love them all
but when making a new tank you do want it to appeal to another group Warrior,Paladin and Dark knight cover a lot of ground theme and personality wise like Templar its cool and id love some bucket helms in this game
but that general Audience most likely are playing paladin
like with HW most people who played DRK and AST where already playing healers and tanks a very small number actually changed to play them