MINDLESS random jibberish
Yeah, I figure the use of random characters is one of the bigger obstacles placed in the way of folks trying lo learn. It's fine for the military, where transmissions are likely to be encrypted, but isn't particularly helpful for amateurs. I wonder how much easier it would be if words (including the usual abbreviations like ES, DE, GM, TU, etc.) and callsigns (including things like '/P' and so on) were used as soon as they could be. The character introduction order might need changing a bit for it to work well.
I also (on a different tack) wonder whether the add one character, then add another, then add another
progression is actually the best way, too. It seems to me it builds a wall, and each new character gets harder to learn. Some programs help a bit by weighting the new characters so they appear more often, but even so the new ones may only appear a handful of times in any given exercise. I suspect it might be much more effective to work through the characters in small sets until they're all covered, then combine the small sets into larger ones, and repeat that until eventually there's just one set.
Of one think I am certain; the Koch method is not the be-all-and-end-all method for learning Morse, at least as far as amateur radio is concerned. It may work for some, and it has some good aspects, but it's only part of the answer, and only for some folk.