I think the way in which the films have been promoted simply boils down to how the producers feel they need to sell the films to the audience rather than what's actually contained in them. After Die Another Day, they needed to push the whole concept of the "reboot" (which is quite funny, since they never really rebooted anything) for a couple of different reasons. First, it was the popular thing to do, given that Batman Begins had just pulled it off surprisingly well. Second, pretty much everyone knew that, after Die Another Day, the series need to have some kind of a reset to bring things back to reality. There wasn't anywhere else to go with invisible cars, space lasers, and ice palaces, so they sold the public on the concept of a reboot.
Skyfall, on the other hand, needed to be promoted as after the public rejected Quantum of Solace as, as is said often around here, "not a real Bond film". They had to promote Skyfall that way, otherwise some in the general population that were on the fence after Quantum of Solace may not have returned.
Regarding Blofeld, I don't doubt that he'll reappear at some point in the near future. They made so much money off of a film that is essentially all about nostalgia and how the old ways are better that it's only a matter of time before they go back and start reintroducing some of the characters from the older films.
Edited by tdalton, 22 December 2012 - 10:39 PM.