I think I would ask why?

Those bands produced the music they did because of the time, which was late 1960s early 1970s. They have taken that particular style about as far as it will go.

Later musicians being inspired by this, will not be able to produce music with this same 'freshness'. so there is not much point in trying.

They will however be able to take that influence and move it on, as many fine young bands have done and are doing.