In your comment you make a number of sweeping generalisations without supporting evidence or specifying what you mean. For example: “If Intelligence is controlled-for, then the effect of Openness disappears.” This statement is not only overly-general, it does not specify what effects openness are referred to. Additionally, I am aware of a number of studies that contradict this assertion.

For example, a study comparing schizotypy, openness to experience, and intelligence (assessed by Raven’s matrices) found that openness to experience significantly predicted creativity even when controlling for intelligence. (See Schizotypy versus openness and intelligence as predictors of creativity.)

A number of other separate studies examining predictors of general knowledge have found that IQ and openness to experience independently predict this outcome variable. E.g. see Cognitive ability, learning approaches and personality correlates of general knowledge. These studies indicate that openness does possess predictive power beyond intelligence.

You close by concluding: “Take home message: all research on so-called Openness is either ignorant, incompetent — or (usually) both.” This is a massive over-generalization, again not supported by evidence. Unless, you have reviewed every single study on the subject, this is an unreasonable statement to make on its face. I would suggest that there is a large body of research on this personality trait that indicates that it is more than “merely ‘the personality type of intelligent people in Western-type societies’ (but rather badly conceptualized).”

Personality is supposed to be independent of intelligence. Personality is a separate explanatory variable which can be seen after Intelligence is controlled for.

If Intelligence is controlled for, then the effect of Openness disappears, because Openness is merely “the personality type of intelligent people in Western-type societies” — but rather badly conceptualized.

While the other personality traits (C, E, A and N), which derive essentially from H.J. Eysenck, are robust to personality differences — especially in college populations which provide most of the subjects — Openness is not.

Openness is merely a (weak) correlate of IQ (in Western Societies) — plus noise and cross-contamination from other personality traits, e.g. a little bit of Psychoticism or Schizotypy.

Take home message: all research on so-called Openness is either ignorant, incompetent, or (usually) both.