In any sport its up to the referee to check the ball to make sure its regulation. Ultimately it comes down to the refs failing to do their job - a recurring theme with the NFL. The fact that there was gamesmanship going on...so what. It's part of the sport and always has been.
The refs did check the balls, it is quite obvious that they were toyed with after they had been approved by the officiating crew. To further point out how asinine your comment is, it only took a few plays for the refs to realize that something was wrong with the footballs and they were immediately substituted in with properly inflated balls.
Um, no, it didn't. The balls were not reported "soft" until halftime when Brady was picked off. This was well-documented when the story broke down yesterday.
Which brings us full circle to the following question: how did the officials, who handle every ball after every snap (both Pats balls and Colts balls) didn't see anything wrong, and one Colts player suddenly figured out something is wrong from one touch. I mean, wouldn't it be immediately obvious to an official that the Pats balls were noticeably softer than Colts balls?
Also, the narrative of the story has suddenly changed from "balls were underinflated by 2 PSI" to "balls were underinflated by up to 2 PSI". So go figure.