Why is there the orange damage indicator rather than the blood splatter?
It isn't a damage indicator, it is the "Combat Intuition" ability. It's points in the direction where an enemy is aiming at you.
Why is barely anyone using SMART?
Most likely a mixture of 2 things. 1) SMART is anew feature and 2) For a lot of people playing Brink , this is probably their first time seeing the game - they don't about things like we do.
They probably aren't using SMART, because they are so used to how games play without it - they don;t think to use it.