Australian Open Tennis

I just read an interview someone conducted with Rafael Nadal after his second round match. Apparently, the guy playing Nadal hit at him twice, once it caught Nadal's finger and the other time it caught his racquet instead of hitting him. That's something I've never understood about tennis. If the object is to keep the ball from coming back across the net to you, then why do the players regularly hit the ball to the other player? Why not hit away from the player and make the player run? I don't think these two incidents in this match were accidents. Players of that caliber can play without hitting each other with the ball. But Nadal won so neener, neener as they say to the other guy.