To answer the original question first, if it drives you crazy, then you get in there and show us how it's done, big man. You specifically name people in the UFC and Pride........well, they made it there for a reason.....and one of the reasons is not because their guard sucked. Like BRR said, in MMA the guards are going to be a little lower than typical stances in boxing and kickboxing because there are more options of fighting. Fighters are now starting to experiment with different forms and techniques in MMA. Look at David Louiseau and his spinning back kicks, jump kicks, flying knees, etc. Even in boxing, you're starting to see alot of the lighter weight classes drop their lead hand, or their jab hand, all the way down to their side and just keep their power hand, or cross hand, up.
Then you call out how Chuck Liddell has a bad guard and drops his hands down too much! That's kind of silly. Chuck Liddell might be one of the most dangerous fighters in the Light Heavyweight class to this day. Let it be known that Chuck was a D-I wrestler and fought in K-1. He's beaten some of the toughest fighters out there. He's beaten Tito Ortiz, Vitor Belfort, avenged his loss against Jeremy Horn and Randy Couture. If Chuck wants to drop his hands down to his balls, that's his perrogative. He wears the belt, he knows what he's doing.