Even tho other presidents have been seen with their foot on the same desk, it wasn’t as shocking as that photo, because the world knows it was a loaded message. People believe he is a Islamist and at war with anyone who isn’t.
That is what people see and responded to.
Not the same way, though. The other presidents were resting their HEELS against the TOP of the desk, which might scuff up their shoes but not the desk. Obama consistently rests the SOLE of his foot on the EDGE of the desk, which would not only damage the desk but get it dirty as well. I wouldn't do that to a $5 garage sale coffee table.
What a jerk.