I liked Gene's idea that humans would more fully settle their emotional differences and get along with near-zero conflict. At least in theory. For the sake of compelling drama and situations, a ship full of people who act like they're all on a cocktail of Zoloft and Prozac is going to get boring very quickly.
A quick backstory: "A Taste of Armageddon" has Kirk saying "We have a history of barbarism, but we don't have to be
today." (Delivered with eloquence by the same Shatner who'd tell fans 20 years later to get a life with equal fervor, LOL!)
80 years later, a span of four generations - depending on how you define a generation in terms of years and if a generation is a set period of years - we see the culmination of that. Humans are now more like Vulcans for the most part, though Geordi would build large scale model ships for Moriarty to wreck and AI would learn how to paint, with everyone frothing over that instead of finding spirit in what their fellow biological beings (no longer do).
I appreciate what TNG was trying to do, but TOS - in regards to Kirk's own lamentation - is
better. Even if TNG outdid TOS in other areas of narrative.
Which might be why I
adore DS9 - the characters are like "TOS on steroids". I'd make an allusion to a galactic-scale comparison to TOS except, as far as corny jokes go, that one could provide enough main ingredient filler for 42 factories' worth of sugar frosted cereal...
DS9 also had an array of narrative freedoms you couldn't begin to see during TOS, like characters such as regarding backstories and narrative for Ben, Eddington, Kira, Bashier, Dax, Odo, Garak, Worf, or anyone else - and DS9 is all the richer because of it The closest parallel might be "Blake's 7", a motley crew of disparate individuals in an uneasy alliance but for radically different underlying reasons. When people say DS9 is the closest Trek to TOS, they're right. Not because the wormhole leads to another wild west with the station being the wagon train, no, DS9 takes the premise and runs with it. How it works in tandem with TNG's
shiny happy people motif is a miracle in of itself, but it all gels wonderfully.
Though TOS did have stories like "The Immunity Syndrome", melding high concept sci-fi with some interesting philosophy and relativity (e.g. big amoeba is a virus and humankind is engaging in space travel to cure the galaxy of what could be quite the big terminal disease), along with the requisite Spock/McCoy bickering that has a proto-DS9 feel to it in some ways.
TNG did try to bring in conflict - Maddox vs Data, Riker vs Shelby, Geordi vs Data (at least the occasional bit in season 2), Dr Pulaski (THE most underrated character ever), Ensign Ro (she hit it off with Guinan off the bat and they made a
wonderful double-act)...
But lazy? IMHO, naah, not when Gene had a newer vision for Trek to show his belief of humankind's
evolution. (So if you find a Star Trek fan who's also a fan of the new wave music band Devo, do make friends with them!

)