If the printing press or web were proposed as research topics by a new PhD student today, they'd probably be laughed out of the room. But if they were proposed by someone with credibility, who knows what research is like from top to bottom, in a EUR2M grant proposal with a good demonstration of how the new ideas relate to existing work, featuring an appropriate-sized team and a detailed risk management plan up-front -- they'd be funded.
EDIT: I would also argue that developments like the printing press and the world wide web would have been difficult to justify as incremental extensions of existing work.
I'm not saying these developments came from nowhere, nor that they didn't build on previous work. I'm specifically arguing against the idea that it's fruitful to just focus on work that would be seen as incremental improvements on existing work.