I split this out of a forthcoming "best of links" post so I could
discuss it in tedious detail. The link in question is a
full-throated defense of Star Trek: Voyager which sparked a
lively conversation between Sumana and myself back in
August. Sumana has long despised Voyager, and on the whole
my verdict is "not so great". But there are some excellent episodes, and it did get better over time.
When Voyager was on the air, my problem with it was I didn't like the writing. As I watched it later I discovered another
problem: the supporting cast is redundant. Most Trek
supporting casts have an air of blandness (this is, in a nutshell, why DS9
is the best Trek series: pretty much the entire recurring cast
is well-developed), but in VOY a lot of characters
are just unnecessary.
Specifically, you don't need Chakotay, Tom Paris, or Harry Kim. You
just need Tuvok. Whenever one of those three characters has a scene,
it would be a better show if that were Tuvok's scene. You're probably
thinking: "What about the episode where Paris learned a valuable
lesson about blah? That wouldn't make sense with Tuvok!" Here's the
thing: that episode was lousy. Pretty much every episode where these
three characters act on their own initiative (as opposed to following
orders) is lousy. But once those characters existed and the actors had contracts, the writers had to use them, and it watered down the plomeek soup.
Once we started talking about this, Sumana and I started trying to
compress the casts of other Trek shows. The point is not to
eliminate characters that we don't like--we love almost all these
characters--but to try to get a similar cast with fewer characters, so
that every character can be essential to almost every episode. This is
a ruthless exercise in minimalism.
What's the point? Well, all these characters looked good in the series bible, but some of them didn't pan out. Some of them consistently bombed, some were underused. The thing is, you don't know ahead of time. A series bible is like a meta-screenplay. It can be implemented well or badly, and the final verdict doesn't come in until the end of the series.
This exercise is the flip side of tie-in novels and fan fiction. Instead of fleshing out the underused characters and exploring the ignored relationships, it lets us see which parts of the show were absolutely necessary to get the stories we liked. If you totally disagree with what Sumana and I like about Trek shows, you can probably express that disagreement in terms of your minimal cast.
Now on with the show. When I think Star Trek and "ruthless exercise in
minimalism", I think of the original series. You can tell almost every
TOS story with just Kirk, Spock, and McCoy. Everybody knows
that. But you gotta have some other characters to spread the dialogue
out, so let's dig deeper.
Do you need both Chekov and Sulu? Nope! TOS got along for a full
season without Chekov. Do you need both Scotty and Spock? Not really!
Let Spock fix the engines himself instead of telling Scotty to fix
Sumana took this opportunity to complain about the fact that Uhura,
a chronically overlooked main character, is the only woman in TOS's main
cast. I suggested making McCoy a woman. Sumana pointed out that they
did exactly that in TNG, and nobody liked Dr. Pulaski. This had
me stumped for a while, but now I have the solution: have Nichelle
Nichols play McCoy instead of Uhura. Who would complain? Well, DeForest Kelley fans would complain, but look, now DeForest Kelley can play Khan. (Second-best solution: combine Scotty with Uhura instead of with Spock.)
Now that you see how the game works, back to VOY. As above, Tuvok subsumes Chakotay, Paris, and Kim. Apart from that, my suggestions are pretty minor. Seven of Nine can replace Kes--in fact, she did. With their powers combined, Seven and the Doctor can replace Neelix. Seven can also replace Torres, or Torres and the Doctor combined can replace Seven. But honestly I'd be perfectly happy with the Tuvok thing. You can tell most good VOY stories
with Janeway, Tuvok, and Seven, but it's a stretch.
DS9 did an amazing job of developing a huge cast, so
objectively speaking it doesn't need this exercise, but that's what makes it such a ruthless exercise. No one is spared! The
TNG imports are out: Kira can do O'Brien's job, and Odo can do
Worf's. Dax and Bashir can be combined. You still need Quark, but he
can be a recurring character, like Rom, instead of a marquee
Sumana and I had a lot of fun messing with TNG, because it's
the Trek we both grew up with. And TNG shows that major
characters can just leave a show. The show didn't drastically change
when Tasha Yar died, when Beverly Crusher left (or when she came
back), or when Wesley Crusher left.
It's not much of an exaggeration to say you can tell all the
interesting TNG stories with just Picard and Data. But you
can't run the day-to-day business of Star Trek with just two
characters, so let's add some more.
I think we have to leave Worf in place, especially since we got rid of him on DS9. The big question here is what to do with Riker, Troi, and Crusher,
TNG's equivalents of Chakotay, Paris, and Kim. The situation's
better than VOY because there's about 1.5 interesting
characters between the three of them--but how to arrange them? The
obvious thing to do is combine the two medical types, but the
resulting character isn't any more interesting than Troi alone.
That's why we prefer to merge Troi with Riker and create a real XO
character, someone responsible for mediating between the captain and
crew. Either Marina Sirtis or Jonathan Frakes could play this
character well. With this character you can play up Picard's reserve,
make him a little less of a nice guy. If Picard is the captain
everybody admires but nobody positively likes, this Troi-Riker
character becomes the most interesting character on the show! Picard's
more interesting, too. Combining characters
doesn't just tighten up the show, it creates new possibilities.
You don't need Geordi LaForge when you have Data. If you really want to
keep him (I do, he's my favorite TNG character), have him replace Crusher, but I
don't think TNG needs a main-character doctor at all. Crusher
was incredibly underused; have recurring guest stars do the sickbay
OK, one more. I haven't been messing with the commanders, because
if you change the commander character you change the whole tone of the
show. But on ENT, Captain Archer isn't the strongest
character: Tucker is. You can tell almost every good ENT story
with Tucker, T'Pol, and Phlox. You'll need an
Archer+Reed+Mayweather+Sato character to spread out the dialogue, but
with those four you're good to go. A Trek show where half the
command staff are aliens would be really interesting, and quite
appropriate for the ENT era.
 "Demon" and "Course: Oblivion" are among my favorite hours of
Trek. For Sumana-like skeptics, some more excellent VOY off the top of my head: the "Equinox" two-parter (which shows what
would have happened if VOY had been the Battlestar
Galactica reboot), "Body and Soul", "Message in a
Bottle". VOY also had some excellent stories about
storytelling (eg. "Muse" and "Living Witness"), something that
TNG tried occasionally but it never worked. DS9 fans especially should watch "Message in a Bottle" for its view into the Dominion War.
 Here's the kind of thing I come up with when I mess with the
commanders. The DS9 pilot focuses on the great Federation
diplomat Curzon Dax (Terry Farrell), who's been posted to the Bajoran
system following the discovery of a strategically significant
wormhole. Halfway through the pilot, Curzon is assassinated by Bajoran
extremists trying to disrupt an ancient prophecy. The Dax symbiont
must be saved at any cost, but the only Trill within range is Ezri
Tigan (Avery Brooks), the troubled first officer of a
nearby Federation starship. Yes, I said it. Avery Brooks plays Ezri
Dax as the main character of DS9.
 Yeah, Phlox. He did kill a whole species that one time, but
take him away and you no longer have ENT. Phlox's strength as a
character comes from the fact that, by human standards, he's
insaaaaane. IMO one of the most realistic depictions of a "human-like"
alien in Trek. (Sumana asked me to add this disclaimer: "We cannot be sure how realistic this depiction is, because hypotheses about the behavior of imaginary aliens cannot be tested.")