Sure, language moves on, yada yada, and usage shifts to what people most like the sound of, and “enormity” in particular somehow sounds more erudite than “enormousness”, so many people think it must be a more correct word for something that is huge or immense. Yeah, no.
So, the proper meaning of enormity.
The Navy might just take exception to your description of the “enormity” of the challenge they face in coordinating today’s International Fleet Review celebrations on Sydney Harbour, journalist dude. I’m certain that they regard today’s operation as the exact opposite of an excessively wicked operation, in fact. They may well be somewhat tense due to the immensity of scale of manoeuvres, of course.
Like so many other usage shifts, the boat may well have sailed on this one (<= see what I did there?). I reserve my right to continue to grumble about it. Humbug.