I am convinced the producers of James Bond films live in a time warp in which it is perpetually 1963, the Cold War is still on, the sexual revolution is in full momentum, smoking and drinking are cultural norms, the British Empire still plays a part in determining world affairs, and there is actually an audience willing to pay seven dollars to see a James Bond movie set in a world in which the above conditions no longer exist.
Mike Myers conclusively proved in the Austin Powers trilogy that James Bond is an anachronism in a post-1980s world. Every aspect of the 007 genre---misogyny, promiscuity, hedonism, substance abuse, unhealthy living, snobby tastes in food and drink, and a mistaken belief that judo chops to the shoulder can induce unconsciousness---is unintentionally funny to a politically correct 21st century.
James Bond was the product of specific historical circumstances---the emergence of the Cold War, the Kim Philby scandal, British envy of American supremacy, and an overoptimistic faith in technological innovations borne out of the American space program---that do not work when superimposed on a different set of historical circumstances.
007 purists assert that the series went downhill gradually when Sean Connery abandoned the role, then suddenly after Roger Moore departed. While I agree somewhat that the actors who followed Connery were unable to reproduce his success, I also believe that Connery's performances declined in successive movies, especially in Diamonds Are Forever (the first time I saw the film I could not stop laughing because Connery gained weight and used a hairpiece with a pompadour so that he looked like Alabama segregationist George Wallace).
I think the quality of the films had less to do with casting and more to do with the producers' desperate attempts to make the post-1960s Bond films relevant to contemporary events (Live and Let Die=black power movements, Moonraker=Skylab and Soyuz, Octopussy and A View to A Kill=detente, glasnost, and cooperation between the Communist World and Free World).
Ian Fleming's books are not as adaptable as William Shakespeare's plays. Bond's natural setting---London clubland, dalliances with married women in St. John's Wood and Mayfair, the pre-tourist-and-cruise-ship Caribbean islands---is infinitely more interesting than the high-technocracy of the twenty-first century, where men like "Q" have replaced 007 as the superstars of modern intelligence agencies.