Lots of good comments here. My view is based on verticality. If the defender stays in his vertical plane and blocks the ball, and then there is contact, no foul. Usually if the defender stays in his vertical plane the contact is initiated by the offense player. If the defernder goes out of his vertical plane, regardless if it is after the shot, it's a foul unless it is deemed incidental. Keep in mind that a bump that occurs after the shot and moves the offense could put him out of position to get a rebound, catch the blocked shot, receive a quick pass back, etc., so claiming there was "no disadvantage" just because it was after the shot is pretty weak IMO.

On a related note, many officials believe defenders need to be "set" with both feet on the ground in order to get the benefit of a charge call. Wrong. I like to see officials sho have the guts to call a charge when the defender jumps vertically and the ballhandler jumps into the defender, or the defender is moving away (i.e., a step backward or to the side) from the advancing ballhandler (who initiates contact) or is set but is turning to protect himself from the collision.