I agree that the article could be a lot more informative. However, one can actually figure out quite a lot. For instance, since they call it a diode, it means the leaky capacitor you mention is asymmetric, and leaks more easily in one direction than the other. This is born out by the picture, which seems to show two layers of insulator, of different thickness, between the metal layers. And once you have electrical asymmetry, you can start building all sorts of interesting logic. But I agree they do not explain why tunneling through two layers A and B in the order "A then B" should be different from "B then A". Is it because of the direction of applied voltage, or are the insulator materials asymmetric at the molecular level, or is there some deep fact about quantum tunneling that makes it work? I would certainly have liked to see that covered.

Second, in terms of benefits, it seems this device would be far easier, simpler and cheaper to fabricate than a normal PN diode. In a PN diode, you essentially need to arrange a metal wire, a small P-doped semiconductor region, a small N-doped semiconductor region and another metal wire. In addition, the two semiconductor regions need to be insulated from their surroundings somehow. This all requires pretty careful alignment. It looks like the MiM diodes would be self-aligning, in the sense that you could just create a pattern of vertical metal wires on one layer, then overlay the two layers of insulator, followed by a layer of horizontal metal wires. The diodes would form at the points where the wires cross, without any precise alignment being needed. And the fact that the middle layers are insulators would mean no further insulation was necessary. One could probably fabricate giant sheets of these things very cheaply.

Finally, the fact that they can use these for rectifying infrared radiation implies they can operate many orders of magnitude faster than normal CMOS diodes.

Googling a little also hints that MiMs are better at extracting the full energy from incident photons in photovoltaic applications, which could be a useful side benefit, allowing one to efficiently convert optical or infrared radiation into DC current with a single type of device. But I'm just guessing, an expert would need to confirm that.

In summary, I agree this article could be a lot better. However, I have seen a lot worse, and it does seem to be alerting us to something which could turn out to be important.