I like TOS and much of TNG the best. I'm going to turn the whole "character development" thing on it's head and say that often "character development" means "soap opera"
What made TOS work so well is that they started out with some pretty basic character types and left them alone. Kirk's personality didn't change or grow througout the series, Kirk was "Kirk". Instead, the attention was on the stories, and the stories were, for the most part, very good stories. Explorations of humanity, of political ideas, of the impact of technology on us, of different cultures and how we would react to them. For the most part TNG followed this, especially with Data and with Q. Data was used to explore what it meant to be human, Q was used to explore what humans could become if they grew culturally, etc... The stories worked; they attmpted to be challenging, to try to stretch your imagination and explore new ways f looking at problems. TOS did what sci-fi does best, use an alternative setting to explore basic questions of humanity.
And that's where I lost interest in DS9, especially. TOS had "does humanity need gods?", TNG had "Has humanity grown enough to be worthy of not wiping out of existance?", DS9 had "little Ferengi kid wants to join Star Fleet". Bah... (TNG ended up getting bogged down toward the end, as well)
To be honest, I think a lot of time "character development" is a substitute for "lack of good ideas". By that I mean that you can learn to do 'character development' just by going to writing classes. Well or poorly, just about anyone can do it. To come up with *really* creative stories that challenge the viewer as they challenge the characters requires a really creative mind, and i's a lot harder to just hire a bunch of writers to do. So instead of moving stories, you get cliched stories that focus on 'character development', because it's a cheap and easy way out for the writers and the producers
I didn't watch too much of Voyager but from the start I thought "it's going to suffer 'Battlestar Galactica' syndrome" meaning that if you start
a series based on a quest, someday the quest has to come to an end or you just get redundant, repetitive, and strecthed out excuses for "well we didn't get home *this* week...what's next?"
Not that 'character development' in a TV series is bad in it's own right, but therte are a *heck* of a lot of TV shows that use this as the main motivator. Roddenberry's original vision for Star Trek was that humanity had overcome many of it's vices so it was time to go out and explore the galaxy and see how humanity meet the galalxy, and this was a way of mirroring back to our own culture today (and because of this, there was little time for 'character developement' amongs the principles and indeed as the principles represent 'types' of humaity, you couldn't really have character development, because the characters stop reperesenting aspects of 'us'). TOS did this very well, TNG did it OK...great in some palces, sappy in others. B&B didn't seem to have a clue so we got soap operas disguised as sci-fi
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