And without Nichelle Nichols on Star Trek, she wouldn't have been hired by NASA and then we wouldn't have had Sally Ride, so she is a legitimate space hero.
It was TNG that really established an ensemble cast formula; TOS was Kirk-Spock-McCoy and the rest. It took TNG a couple seasons before they got the idea of a true ensemble cast where everyone gets to star in some episodes. TOS wouldn't have had more than one episode starring Reginald Barcklay with Geordi and Dianna in supporting roles, but TNG had at least two.