Why was THIS play a touchdown, and Calvin Johnson's catch NOT a touchdown?

Well, that was a long time ago, that super bowl, so the rules have been updated a bit, though that video was definitely not a catch. But the rule today states that the receiver that is going to the ground must maintain control of the ball all the way to the ground, no matter how long that might take. So, by the letter and the law, the correct call was made. By common sense from any person who has ever watched a football game, that was a touchdown.