The point is that hashrate is what's desirable (and directly linked to Bitcoin), not energy use.
If someone improves efficiency such that energy use is decreased while hashrate increases, THAT is desirable.
Of course, in the real world every time efficiency increases, energy usage goes UP, not down, because the efficient use of energy makes it more affordable and thus available to a wider market of users.
But the energy consumption is incidental to the generation of hash, or else we'd all just be firing up the least efficient (but cheapest) miners available in order to consume as much energy as possible, which is obviously not the case.