This needs naming. The ists are easy to recognize: designists are to designers as jocks are to athletes. Most athletes are not jocks; most jocks are not athletes; but jocks worship athletes. Likewise designists worship designers. The ism is also simple: its creed being that design is necessary and sufficient.
This ism is accusable on three grounds. It is irresponsible: the designist holds the designer to no responsibilities, even to design—what would it would even mean for a designer to sell out? It is amoral: designists respond shamelessly to good design in the service of Soviet propaganda, and the response is more convincing than the shame where Nazi hardware is concerned. It is brutal: good design is like good aim. To praise the shot without asking who got shot and why defines brutality.
Designism is dogmatic mediocrity.
Designers must be dogmatic, because they are responsible for just the part of a thing with the least, or without any, constraints. It is the job of a designer to deflate possibility with orthodoxy, to halve the possible into the good and the gauche, and halve it again, until it contracts to the practicable. (Water cannot boil in a perfectly clean pot; some grain must be present for the bubbles to coalesce around. Likewise, without grains of dogma, there is no inspiration.)
Designers must be mediocre, because design targets the masses—in possession or in aspiration. Designers must be able to trust that their own reactions represent the average reaction. Skilled as they may become, designers cannot design unless they remain mediocre in their souls.
Designers are dogmatic and mediocre, but they are not therefore dogmatic about mediocrity. That is the extra step that makes the ism. Review the creed. If design is necessary, then what does is not deduced from the dogmas of design cannot be good. If design is sufficient, then what does not appeal to mediocrity must be a mistake.
Nobody defends bad design; not even I do. But I do not trust design. Bad design vellicates, but good design sedates. Influence, manipulation, and persuasion can deviate our intentions, but not deflect them. They affect, but they do not take. Design harmonizes the things that are intruded into our lives with the patterns of our perception and attention, makes them blend in or fit in. Design camouflauges; design encysts.
Of course it is the intrusion, not the design, that is good or bad. Design is analgesic. Analgesics make life better, they give us control over pain; but when the leech injects them, we are fatted on without noticing the loss. Designism confuses the mechanism with the thing that uses the mechanism, and applies more leeches for a deeper cure.