Bart
I think the "worse results" bit wasn't what he was after; the emotional response was. So, sure, "mentally" harder could factor in -- make no mistake, he wanted to create courses that challenged the very best, the average, and the mediocre alike -- but so, too, could easier. There was a method to his fooling, and it was the experience, the emotional response. That could mean harder or that could mean easier; the word Mac might have chosen instead was "heroic."
Therefore, the notion of any deceptions he employed that made a hole or shot more difficult misses the mark a bit -- IMHO.
Consider this passage from "Golf Architecture:
It is largely a question of the spirit in which the problem is approached. Does the player look upon it from the "card and pencil" point of view and condemn anything that has disturbed his steady series of threes and fours, or does he approach the question in the "spirit of adventure" of the true sportsman?...
It does not by any means follow that when a player condemns a hole in particularly vigorous language he really dislikes it. It may be a source of pleasure to his subconscious mind. Although condemning it, he may be longing to play it again so as to conquer its difficulties.
Emphases added.
Also, his ideal was for match play not medal or "card and pencil" play. This, too, should put his comments re deception and difficulty in a different light. Another passage from "Golf Architecture":
Successfully carrying or skirting a bunker of an alarming or impressive appearance is always a source of satisfaction to the golfer, and yet it is hazards of this description which so often give rise to criticism by the unsuccessful player. At first sight he looks upon it as grossly unfair that, of two shots within a few inches of each other, the one should be hopelessly buried in a bunker and the other should be in an ideal position.
However, on further consideration he will realize that, as in dog-legged holes, this is the chief characteristic of all good holes.
Holes of this description not only cater for great judgment, but great skill: a man who has such confidence that he can place his ball within a few feet of his objective gains a big advantage over a faint-hearted opponent who dare not take similar risks.
As far as his praise of TOC or his use of blindness in some of his designs, Mackenzie wrote there "are few, if any, ideal two or three shot holes in existence." Apparently, he found criticism with virtually everything he saw, including his own designs: he wrote of how some of his best holes could have been improved, sometimes to the effect of improving the green's visibility. (This, even as he was a master of self-promotion.)
So: in his writings he reached for Platonic ideals in his writings, even as he recognized such ideals could not survive the real world, and might not even be "ideal" out there.
Mark