My understanding is that Roddenberry wanted no conflict among the main characters, because he felt humanity in general and Starfleet officers in particular would be above that. But that often gets twisted -- oftentimes by the writers themselves -- as if Roddenberry wanted no conflict at all. Which is just blatantly ridiculous, since there was plenty of conflict right there in the parts of "Encounter at Farpoint" that he wrote.Still, people exaggerate when they say Roddenberry insisted on no conflict in TNG. The rule as I understand it was actually "no petty conflict" -- nothing arising simply from people being emotionally dysfunctional or immature or mean-spirited or assuming the worst of each other, the usual sitcom or soap opera formulas. I've seen TNG writers say this was a good thing in a way, because it forced them to avoid the lazy shortcuts for generating conflict that writers too often fall back on, and challenged them to come up with conflicts that were actually meaningful, that could arise between well-adjusted people who respected each other but who had fundamentally different priorities or came down on different sides of a complex issue with no easy answers.
Brannon Braga gets a lof of hate at times, but I really respect the fact that he doesn't trash Roddenberry but instead says Roddenberry's directives challenged him to approach stories in new and different ways and that he enjoyed the challenge.