"What? We don't need stupid gadgets to make a good spy film? Who knew?"
The Bond people knew. They did it in 1989 with License to Kill, the public just wasn't ready for it at the time (and Timothy Dalton never really caught on in the US, unfortunately). The Bourne films influenced Casino Royale to a certain extent, but it seemed to me they just decided the time was right to go back to the direction they tried 15 years earlier.
ETA: In fact, gadget free Bond comes 'round in cycles. Dr. No, From Russia With Love, On Her Majesty's Secret Service, and For Your Eyes Only all have few, if any, gadgets.
License To Kill had plenty of gadgets in it they even put Q in the field to arm Bond.