More specifically, The Humble Programmer is about "professionalizing" programming. In the '50s and '60s, programmers justified clever tricks due to the strict constraints of early machines. Dijsktra is saying enough already with that, we need to move to a neutral style and favor clarity above all else, so programmers can understand others' work. Esolangs, which often annihilate readability, give an excuse to show off technical feats that aren't justified in mainstream code, a return to the "Wild West" (as Backus put it) or early computing.
More specifically, The Humble Programmer is about "professionalizing" programming. In the '50s and '60s, programmers justified clever tricks due to the strict constraints of early machines. Dijsktra is saying enough already with that, we need to move to a neutral style and favor clarity above all else, so programmers can understand others' work. Esolangs, which often annihilate readability, give an excuse to show off technical feats that aren't justified in mainstream code, a return to the "Wild West" (as Backus put it) or early computing.