Sadly most players think tank damage is negligible. This is because we don't have an in-game way of knowing the damage done or the DPS for the fights.
This is not true by any means. A tank can do around 50% of a regular DPS damage, or even more than 50% if the tank is OT with STR accessories.
Like most others said on this thread, best thing you can do is use STR accessories and swap stat point from VIT to STR.