I would say that the most important thing is to let researchers expand their imaginations, because that's what makes real progress possible. As the physicist Einstein said:
“Imagination is more important than knowledge.”
The more you tell people what to do, the less progress you can make in the long run. So it's very important to let fundamental researchers choose for themselves and find out what's truly of interest. Some will be left in the dust, while others will make extraordinary discoveries. That's the only way to make serious progress, to make the quantum leap, if I can put it that way, as opposed to just developing the technology in small steps.