The first time they introduced the Eugenics Wars set in the 1990s, Spock called it the last world war. Pike in SNW elaborated that it was part of the escalating conflict that went nuclear as WW3 decades later.
I'd say TNG mostly stopped exploring new frontiers halfway through season 1. Farpoint promised exploration, but soon the ship is ferrying diplomats and scientists and answering Federation distress calls. The worlds are new to the audience, but not the characters.
There was a spinoff pitched during TOS called Hopeship featuring M'benga. The pitch for NBC/RCA was that instead of introducing expensive colorful sets, they could stay shipboard and have expensive alien makeup and costumes.
A Quality of Mercy also showed Una in prison, and Those Old Scientists implied she's revered. Did sending that letter prevent Pike from recruiting her lawyer? Things are already not heading down the exact timeline we saw Ortegas alive in.
With one barely mentioned planet, this episode reframed the plot originally designed to hold together TNG, DS9, and Voyager.
Federation authorities insisted the DMZ colonies were recent and had been warned they were disputed territory. They painted a picture like Israeli settlers in Gaza refusing to obey their own government and leave.
But now we have a Federation affiliated colony on Setlik 2 a century earlier.
The UFP's failure to stop the Maquis terrorists always seemed like command wanted the war restarted with plausible deniability. Now the Maquis arguments are stronger. Ceding long-held territory is much easier to call abandonment.
She played the captain of the Lakota later in DS9, Captain Benteen.