Even if Brady would have been caught red-handed, a 4 game suspension is too harsh. There was no definite proof that he was guilty. The 4 game suspension was simply based on a suspicion from the NFL that Brady may have had general knowledge of the deflating.
As others have said, even if he was guilty, this is a relatively minor offense and is the equivalent of a parking ticket or maybe going 10 miles over the speed limit and getting a speeding ticket. It had little to no effect on the final outcome of the AFC championship game. The NFL was clearly trying to make an example out of one of their star players and it ended up backfiring on them.
Goodell needed to be reined in. He's been ruling the NFL like a dictator lately. I'm glad his ego has been checked. I liked him at first, but at this point, I'm ready for a new commissioner.