The Obvious Reason Chess Computers Win is because of their Incredible Brute force Tactical abilities...
But for Me the Real Reasons are that Humans Input into the Chess Programs Opening books!...some going Deeper than (20) Moves! and End Game databases now at (7) Pieces.
People may say that it's OK! Because Humans have the same Information...but there is a difference!
Computers have Strength's that Humans don't...(No Nerves) (No Feelings) (Never get tired) (Cannot be psyched out or Intimidated) (Can Calculate to Incredible Tactical depths) (Etc. ?)
What do Humans have...(Knowledge-Opening books & End game) (Experience) (Deeper Strategy)...these are the things We should keep as Humans!...Giving them to the Computer is Why they Win!
Even though Chess Computers are now Rated at (3000+) ELO 2013 I don't believe they will get our Human Strength's above on there own!... until they are Rated between (3500) – (4000) ELO
So why give it to them Now??
I will Never! accept that a Chess Computer is World Chess Champion against Humans... until a Computer can sit Down :) and Play a Set of Games against the World Human Chess Champion without none of the Human Strengths above being Programmed into them!
The Chess Program has to Play Completely from a Calculating Point of View!
Humans know one Critical mistake in the Opening or End Game is the End! don't let them Know!
When Garry Kasparov Played Deep Blue in 1997 Game (6) and lost? The Reason Why was because...
The Computer is aided by having this knight sacrifice programmed into its opening book. This move had been played in a number of previous high-level games, with White achieving a huge plus score. However, had Deep Blue been on its own, it would probably not have played this.