Keepers lack of foot saves

I can't count the number of times I have seen a goal were a player is coming straight towards the goal line(or maybe a slight angle), but to the side of the goal, and when the player hits the ball hard and low towards the far post, the GK tries to drop his entire freaking body to hand save the ball. This when his foot, which is already on the ground, could and would have easily reached the ball.

A decent example is the second west ham goal today.

Can anyone explain why GKs are so hesitent to use their feet in such a situation. You rarely see one that gets down quick enough to stop this shot.

I understand there is rebound concern, but if you have a very small chance of even stopping the shot, who cares about a rebound? Save the first shot, then worry about whats next.

I played GK for my schools JV team (played field for varisty) for a year because we had no one else due to injury, but I used whatever was need to stop the shot, and the foot saves was so much more natural feeling in those situations that trying to catch-up to a hard hit ball.