Why are UFC fights now 5, 3 min round fights?

2 more rounds are added if the match has a Championship belt on the line. Since GSP is currently the Welterweight Champ, all his matches will be Championship title defense matches, so he has to fight 5 rounds everytime until he loses the title. It's the same reason why boxing also has 10, 3 minute rounds for non title fights and 12, 3 minute rounds for Championship title fights. I believe the extra 2 rounds are supposedly to give the Challenger a chance to win if the match goes to decision since a Champion usually has the advantage in a title match in terms of points, especially if the Champ does not engage and just plays a defensive game, because unless the challenger KO's the Champ, he needs to bring the fight to the Champ and show constant aggression and pressure to win in the judges' scorecards.