This is actually a perfect example of how Craig's Bond resembles the Bond of the books. James Bond was never meant to be this awesome guy, he has always been "On Her Majesty's Secret Service", a government agent who does everything for the Crown. He's not supposed to enjoy life; no one should ever enjoy killing for a living. He's an assassin, but it's what he's paid to do. The books even describe how he's not supposed to fall in love, because that creates attachments that can be used against you. When he does fall in love, it bites him in the ass, and he learns a lesson. In Casino Royale, the line "the bitch is dead" is a direct lift from the book, where he realizes he was fooled by love but as a spy he's not allowed that luxury.
I've heard the "bookBond" argument many times, and you make it better than most. But while I might at one time have found it persuasive, I don't have much interest in it anymore. MovieBond has had 50 years of storied cinematic history to become his own thing, and I'm not sure there's any inherent virtue in making the character slavishly "faithful to Fleming" -- at least not if it gives us Craig's glum interpretation as the result.
FWIW, Dalton also based his version of Bond on the literary source material, and was lauded by fans for doing so. Somehow, though, his Bond came out flinty and intense, but not perpetually po-faced like the current incarnation. Indeed, Dalton's may well be my favorite take on the character.