People certainly have-gotten and are-getting dumber - as has now become objectively known from the slowing of reaction times over the past century- and this is a big big problem for science, technology and capability...
(since there are now very few geniuses and therefore not enough breakthroughs to compensate for the collapsed efficiency due to bureaucracy and Leftism and thereby sustain the world's current population).
But the constant complaint of how dumb are the people in charge, is misplaced.
Because in situations where there are extremely intelligent people in charge they mess-up just the same or worse, because they are insane. Insane is worse than dumb.
It is the psychotic behaviour of modern secular Leftists that is the problem, since they partly cannot, and partly will not, understand basic realities.
It doesn't take very much intelligence to understand basic realities - it just takes common sense and the capacity to learn from experience; but these traits are precisely what is absent from the modern rulers of the large powerful social systems (government, law, education, the mass media etc).
Absent common sense and the capacity to learn from experience, cleverness will make things worse - indeed there is no perceivable limit to the extent and ways in which clever-psychotic people can mess-up (as can be seen from the horrible history of communism).
The number one trait most needed, and most lacking, is not intelligence but honesty. Ruthless and total and habitual honesty. It's worth incomparably more than one or two standard deviations of IQ.