One could argue that it's easier to suspend your disbelief for a film that requires you to suspend your disbelief over everything than to do it for part of a film that proclaims itself to be gritty and grounded in realism?
*shrugs* For me, it's not even a matter of suspension of disbelief. I simply don't like James-Bond-as-camp. The character and the concept just don't work for me except in a very serious, dark, Naturalistic context.
James Bond is like Dr Who, it shouldn't ever be taken that