Batting the puck into the net off an opponent

[John Robertson]

I'm not a referee, just a fan. Here's my question:

Wild scramble in front of the Team A's net. The puck pops into the air. A player from Team B swats the puck with his hand. The puck hits Team A's goaltender's leg and goes into the net. No goal, right?

Same situation, except that after the puck is swatted it deflects off another Team A player's leg (not the goalie) and then goes into the net. I understand this should be ruled a goal.

If this is true it doesn't make sense to me. Why should the rule be different if the puck goes in off a goalie or a defenceman?