Opening Preparation - Good or Bad for the Game?

Today is Nov 11, 2014. Anand won Game 3 of the WC match with white pieces against Carlsen. Many criticized Anand that he won the game mainly because of his opening prep. So, is opening preparation good or bad for the game?

Opening prep has been there for decades. This includes Fischer then (I'm sure Fischer Trap was a home prep), and Carlsen today. The only difference now (but a huge one) is the use of computers. With everyone using the computers, it requires human novelty anyways to surprise the opponent - here computer is used to verify the soundness of the novelty. This is part of chess study just as anyone would study the end game and middle game technics, so what's wrong with it. This should not take away the credit from the player who spent several hours on studying the opening. 960 is certainly another great format, but the classical format comes with the richness of history and evolution of the game over the generations (in other words the opening prep mostly). Names such as Ruy Lopez, Gruenfeld, etc. adds richness to the game. Without more prep, where is the evolution?