If I were to accept, as you do, that managers and workers differ, I would need to identify factors that explain that difference. For example, that managers have X, Y and Z and workers do not, or the other way around. Or something of that sort.
The argument that I proposed stipulates that the forces that promote mediocrity - which on the pain of oversimplification can be described as Taylorisation of every aspect of everyday and professional life - are general in nature and affect all social classes. It used to be that only blue collar jobs were dumbed down and reduced to low skill routines, but right know even professional jobs have been Taylorised - most doctors follow up computerized diagnostic procedures and dispense pre-defined doses of medication, teachers follow up pre-printed by large firms curricula and administer standardized, machine-scored tests, engineers and architects simply put together pre-fabricated elements, managers ape each other in following fashionable trends, and so on.
The pre-fabrication also took over the everyday life. People passively watch shows that are variations on a few primitive formulae predictable as the bowel movement - boy meets girls than looses her only to 'get' her again, the bad guys disrupt the serene American life and almost succeed in carrying out their evil plot, but then a car chase and gun fight ensue and the serene life is restored. Comedy? - most of is not funny at all, and if the shows were not frequently punctuated by mechanically produced laughter, those who watch these shows would yawn most of the time. Laughter is contagious - people laugh when they hear other laughing even if they do not know what's going on.
It appears, therefore that the forces of dumbing down affect every social class in the US - not just the managerial class. People are more likely to hold it against managers than workers, but the main reason is that because they expect more of managers, hence the disappointment if the managers fail to live up to that expectation.
Another comment, the forces of dumbing down are not deterministic - their work depends to a substantial degree on human choices. Some people may choose not be dumbed down for a variety of reasons - from family background to education to personal ethics and to the chemistry of their brains - but it requires a non-trivial effort to resist the temptation.
Wojtek