Because it kills every new idea how to measure personality. 😎

IQ is the king. This is why academic psychologists almost never measure it. If you measure it along with your putatively "new" measure, IQ will kill your ambitions. For the career minded, this is a no go zone. So people prefer to talk about multiple intelligences and EQ, and all these things that do not exist. PERIOD.

No one succeeded in creating a new personality trait which would measure something IQ and Big 5 do not measure.