I am generally kindly disposed towards the late Mr. Sagan, but that quote is shit.
Why? Because the power of intelligence by itself to enlighten is relatively low; only a few things in the "enlightenment" category can be arrived at by sheer brunt cognitive effort. Rather, wisdom derives mainly from the combination of intelligent observation with openness to receiving, evaluating, and incorporating the insights of others, whereas most people do not do as much observing and nowhere remotely near as much openminded listening as they think they do; and the limiting factor in both is far more often one's attitudes than one's IQ. Meanwhile, it promotes and perpetuates the commonplace bullshit that intelligence is the ultimate measure of a person and what is most valuable about them, as opposed to, for example, their actual insights (whatever these might be), their goals (whether accomplished or intended), the content of their character, or how they treat others.