Without wishing to suggest that people shouldn't be observant and vigilant, I wonder if the actions of these passengers would have drawn the same interpretations if they hadn't been of "Middle Eastern appearance".
But the chances are that a major terrorist event is going to be committed by persons of "Middle Eastern appearance". Without infinite resources you have to play your best odds to avoid another attack.
I am, however, in 2 minds as to whether the terrorist threat is as bad as it is made out to be or if the terror industry are playing it up to line their own pockets.