If the tank can hold agro, you just made a tank and spank crappy action game(tera online gold). The tank cant even do decent dps while the mobs chasing everybody else around. From what the demo showed, they attacked the captain with no tank and he was a boss mob. We are guessing they did that not show a tank and spank fight using a tanking class but a more action fight since this is supposed to be a action Tera Gold game.
Why would you even bring a tank with agro moves. It would kill the whole action combat feeling that this games supposed to bring in Tera. It also showed that even though the whole group was to stupid to ever dodge, so called massive damage aoe move. They still didn't need a low damage tank, they were fine with a healer(Tera online Gold). The boss hits to weakly that a tank was not needed and a healer worked out great.