Was there really any internal conflict among the TOS crew? Aside from McCoy occasionally making sport of Spock (and vice-versa), was there really any major discord among Kirk's crew? Both Spock and Data periodically encountered discrimination and prejudice here and there from Starfleet officers who didn't initially know them very well, but there really doesn't seem to be any more internal conflict among the TOS crew than there was among the TNG crew, IMO...
Leonard McCoy was a racist. There was periodic insubordination. Often, especially when Spock was in control of the ship or of a mission there was friction about his decision-making process that went beyond simply saying "I disagree." TOS was infinitely more internally combustable than was initial TNG. Because the people writing it were trying to write a TV series rather than preserve a legacy. This, by the way, was why I chose to do what I did with FEDERATION. I felt STAR TREK, like the Federation in the story, was a victim of its own success and had lost sight of what it meant to make compelling, immediate, relevant television. Nostalgia is death. "Keep moving forward." - Walter Disney
David Gerrold has also commented on the differences between the GR of '67 and the GR of '87. The big difference between the two is that '67 GR was, as noted above, a working writer/producer who was just trying to find a way to tell the stories he wanted to tell and comment on the stuff that bugged him in a television environment that wasn't quite ready for that. Also, he had Bob Justman, Gene Coon, Dorothy Fontana, et al to keep him honest. By the time of TNG's development, writer/producer Gene Roddenberry had been beatified by the fans as "Gene the (mostly) Pius", so that even bringing Justman and Fontana back, with Gerrold as backup, wasn't enough to restrain the rampaging, and now slightly unhinged, ego. I suspect that even Roddenberry knew he wouldn't be able to keep the bit up for long, which was why he took Rick Berman under his wing (to head off another Herb Solow, network-spy-in-residence situation) and make sure that the person who took over would at least get the general concept right.
It's fairly common by fans to praise and criticize Star Trek head honchos. Abrams will eventually be no different than Roddenberry and Berman in that regard. Even the lesser known Harve Bennett, who more or less took over Trek with TWOK, hasn't escaped this, IMO...
IIRC (and this is purely from memory) Gerrold stated (in one of his rant-ish responses to a Roddenberry bio) that Berman was not "hand picked" by Roddenberry. Gerrold stated that Berman was a studio guy who was put in place by Paramount to make sure that Roddenberry's trains ran on time. Gerrold also stated that Gene did not really like Berman on a personal level, either. What hurt TNG, and nearly destroyed it, was the fact that Roddenberry allowed his lawyer (Maizlish) to run stuff, and piss off/alienate Fontanta, Gerrold, and Justman - amongst others I am sure. Only when Maizlish was shown the door, and a good writers room guy was put in, (Piller) that TNG took off. This is the kind of dirty laundry that is and never will be part of the "official" Gene Roddenberry legacy, nor a part of the Paramount PR machine.
Hence, GR's taking Berman under his wing, to undercut his position as the resident "studio guy" placed there to keep Crazy Gene in line (which is what Herb Solow job was, to keep an eye on Roddenberry for the network; he was getting paychecks from both Desilu and NBC, after all). Good point about the blood sucking lawyer. Add in sycophants like Richard Arnold, and you wind up with a very untenable situation.
Herb Solow, "network-spy-in-residence?" I admit, I'm intrigued by this turn of phrase. Care to elaborate?
I don't know anything about the pre-Piller era. I do know, once he was in the big chair, things not only ran smoothly but TNG entered into its greatest period of creative success, far outstripping its predecessor. Michael Piller was a writer's writer. His influence on STAR TREK cannot be overstated. If not for that influence NONE of the subsequent series or films would have existed because the success of TNG would not have existed to allow for them.
You can debate the critical success of the series under Micheal Piller, but wasn't The Next Generation a ratings success prior to him coming aboard?