Yeah, there's some truth to that. A show where the Good Guys always and automatically do the right thing, and there's no question about it can be very facile.
You may know that Harlan Ellison and Gene Roddenberry had such a disagreement about Harlan's version of City on the Edge of Forever. In the original version, the conflict is initiated when a minor crewmember named Beckwith is running drugs on the Enterprise, and kills a crewmemeber about to expose him, then escapes to the Time Planet. Gene wouldn't go for it. "Our people wouldn't act that way." Harlan's attitude was if you stick 430 people on a tin can in deep space, doesn't it stand to reason that you might get a bad apple or two in the barrel? But no, Gene had these ideas about the ultimate perfectability of the human race, and didn't want any non-Boy Scouts in his crew.
The end of the show had a similar problem. In Harlan's version, Kirk is unable to bring himself to keep McCoy from saving Edith Keeler when push comes to shove, and so Spock has to do it for him. In the aired version, whatever angst Kirk may have about it, you know he's going to fall in line and do it when the time comes, and he does. I always found Harlan's version more believable. Old "change the conditions of the test" Kirk wouldn't just accept that somebody had to die, and do it. The way the problem was set up, it wasn't necessary for her to die necessarily, only to be prevented from forming her pacifist movement. There are lots of way of doing that. If Kirk were a real person, he would surely have saved her now, and worried about the other later. The aired version is very facile compared to the story originally intended.
Dark Shadows is similar. It's never a given that anyone is going to do the right thing. When these deeply flawed characters do break through and do the right thing, it means something, because they fail as often as they succeed. But still, I can sympathize with a parent who thought it wasn't a great show for children. It might be good for kids, if the parents sat down afterwards and talked out all the issues that were raised, but many parents don't want to do that, and just use the TV as an electronic babysitter.