Why is being PC (politically correct) so important one will look like a liar to do it?

Why is being PC (politically correct) so important when it makes you look like a liar? It just irks and annoys me when people are so PC they can’t be truthful. When people get caught being real as those embassy cable communications Wikilinks exposed people are still trying to be PC about being busted for not being PC. Instead of trying to duck, dodge, and hide throwing the blame on those who exposed the cable the PC response just comes off as more of a lie as if to say ”I didn’t really mean it like it sounded”. If a team has gone undefeated and crushed their opponents outscoring them 4 to 1 when asked how they will do in the playoffs they always try to say the other team is capable, etc. If they already met them twice in the regular season and whooped them silly both times why not just come out and say ”We played then twice, and we mopped them up both times. They haven’t got anything new so I believe we will win again by at least 2 touchdowns if not 4 as before”?