Personally, I always preferred Q in small doses, so I thought his role in LTK was a bit too much. Desmond Llewellyn was amazing, though, so I don't want to sound like I'm dissing him.
But could it not also be argued that Q's expanded role in Licence to Kill was his finest hour?
So are you proposing that Moneypenny becomes more of a Mary Goodnight-type character? When I think of it that way, I like the idea quite a bit more.
I certainly don't want to turn Moneypenny into a Bond girl and I think Bond sleeping with her at all would go completely against her character. There needs to be a flirtatious relationship and a hint of sexual tension, but not taken too far.
Maybe It would be better to take my original idea down a notch and use her more as an ally within the service, helping Bond gain access to information he shouldn't have or keeping his superiors off his back while he peruses off the book targets. But overall it's her relationship with Bond needs to be what defines the character. I suppose there is a danger in giving her too big a role first time out as it would inevitably have to be cut down for future films, which could cause problems for the actress.
In the past recasting much loved characters such as Moneypenny has proved problematic, I think expanding the role and giving the actress more to do (not to mention casting a good actress who has chemistry with Craig) could help endear her to the audience.