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.

She directed episodes of both "Enterprise" and Star Trek: Enterprise", which each lasted two seasons. The stealth name change was surprising back then.

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.

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.

The new producer took over for season 2. Season 3 is clearly what he imagined 30 years after All Good Things to be like, undoing Generations, and in season 2 he focused on changing the parts of Picard's character that were too major to stuff into season 3.

I've always thought the Romulans weren't just the Vulcans who rejected Surak's teachings, but also any who didn't have the physical ability to follow them.

Originally it was just based on Romulans not expressing any psychic abilities, but Picard also established that sharing personal details publicly as a major taboo. That would track with them being a mix of former enemies who are concerned with suppressing the rivalries that lead to nuclear war.