Its an attribute to the game now...
for two reasons:
-avoids contact and potentially getting hurt
everyone does it dudes, you name him Ive probably seen him dive
rooney, totti, lampard, shaun WP, walcott, adebayour, evra, gerrard, drogba, ronaldo, robinho, messi (but barely ever), kaka
like seriously it happen's loads, just ronaldo sometimes reaches unbeleivable heights of arrogance when he just falls to his knees when he can't reach the ball... he ain't the only one, just the most famous one