The FISA process/court was another one of many negotiated deals during GWB's administration. It did little other than shift professional bureaucrats from one place to another and resulted in spending billions more each year in chasing down "the bad guys."
Bush couldn't have imagined that "the bad guys" were the ones pulling the FISA court's strings, and, I would argue, the FISA court isn't worth the money to fund it if they can't do their own due diligence and insist on the evidence they've been given is viable and correct.
The FISA court is just as guilty as the FBI in failing to see through the FBI's lies.