Time, people and money.
At the moment there seem to be too few staff officers with sufficient time to step back and do futuristic, or holistic thought. They are fully occupied with the here and now. They do not have the time to devote to such thinking.
There will be some concept work in QWI courses, AeroSystems and Staff Colleges but these necessarily occur away from the front line.
Then there is lack on money to drive such concepts through to fruition. One such I recall was the F3 QWI symposium that proposed a SEAD role for the F3. Well argued and wholly realistic but no funds and a dead duck.
On industry led concepts I recall a document on the Trykon Missile (IIRC) written in 1963 by AVRO I think. It was for a TV-guided missile that could be launched outside enemy defences and then navigated down a river or line feature to attack a bridge. It became a MARTEL but of course was never deployed for land attack on bridges.