The Trek franchise reads like a novice writer grappling with current issues and mistakes from previous ideas.
TOS - WW2 submarine warfare. The good guys were good guys, the bad guys were bad guys. Parallel's America's involvement in WW2. Color enhanced to show off capabilities of color TV. Lots of sexy 60s stuff, but a wildly diverse crew. Hard to appreciate now because aside from the skirts, cultural makeup looks like a typical office.
TNG - cold war superpowers. Lots of neutral zone talk and dealing with lesser civilizations. Federation flagship with a psychic and a super-robot deal with interpersonal issues. Very little sex because the boomers grew up, aids freaked people out and lots of preteens watching. First opponent is a god, because well, what other stories can you tell with superpowers and supermen?
DS9 - USSR is gone. Superpowers were boring to write about anyway. Story about a broken down space station on the edge of civilization. They have NOTHING. Maybe the captain, psychic and superman in TNG shouldn't have been white, white and ultrawhite. Brought back some diversity, extended the inter-alien diversity. Grapples with issues of multicultralism in an inclusive society while surrounded by warring cultures.
Voyager - stories about stations which can't move are boring. Story about a ship hopelessly far from anywhere. Easier to write for. Just flip coins to figure out crew diversity and use AD&D encounter tables to randomly generate plots.
Enterprise - Maybe it was too easy to write for Voyager, everything was new. Prequels are hot. Let's delve into the history and backstory.
Enterprise - hmm. maybe should have hired writers which knew the backstory...
"It's a pity because we love the iconic things this series has given us, but at this point I think the franchise is far beyond salvation."