The more you look into it, the more it makes sense. George Lazenby's Bond had his wife murdered in the last film he appeared in, so fans could assume that his 007 retired out of grief. Timothy Dalton's Bond went rogue and was kicked out of MI6. Pierce Brosnan's final outing ended with Bond being abandoned by British intelligence. Next movie, there's a new Bond in the tuxedo and the old one is presumably on a beach somewhere collecting a government pension.
Hell, even the guy who directed Die Another Day believed this theory. Wait, that was the Bond movie with the invisible car, right? Fuck that guy.
Why Does it Make the Film Better?
We like the realism that this theory gives the Bond franchise, particularly since 007 movies have the propensity to fly off the rails every few years (see: Moonraker, Denise Richards as a nuclear physicist, that invisible fucking car).
On the downside, it throws a real monkey wrench in Cracked's patent pending "James Bond Immortality Diet," in which we advise you to hydrate solely with Gordon's and Lillet and to bed at least three secretaries daily.
"C'mon toots. I'm only doing you for my blood pressure."