Roddenberry tried to make a decree that TNG would leave familiar aliens (Vulcans, Klingons, Andorians, Tellarites) behind and to explore new parts of the galaxy. He deliberately set TNG "78 years after Kirk and Spock".
However, GR was coerced to add a Klingon to the bridge (Worf wasn't even in the Writers' Bible for Season One), and they added a Vulcan extra in the corridors. And then a cameo appearance for Dr McCoy. After "Encounter at Farpoint", they even abandoned the extended mission and started to move through familiar areas of space. And for every fan that wanted new material, there were others begging to meet familiar aliens and characters. Eventually we got lots more Klingons, Sarek, Spock, Scotty, Andorians... And even Kirk in the first TNG movie.
Hollywood learns the hard way, over and over, that it is very difficult to sell something too unfamiliar. Hence sequels, prequels, remakes and reboots. Marketing Departments, too, complain that something too unfamiliar is usually a very hard sell. Fans complained that TNG was too different at the same time that other fans were complaining that it was too similar to TOS. We saw the same complaints with each movie, and especially with the Kelvinverse, VGR, ENT and DSC. It's a Kobayashi Maru scenario every time.