I guess the out-universe point is obvious: "this could happen to us" or at least "this is how idiotic we'd look to any visiting alien". In-universe, we can always assume there is a Grand Design behind this, a social experiment of some sort - and the later the experimenter interferes, the less divine his powers need be. Say, deciding that every planet should spawn sapient bipeds in four billion years takes some skill - but deciding that the dominant industrial power of the day should assume Nazi regime and regalia only takes one silver-tongued individual with a catalog from Hugo Boss and another from Krupp.
Omega IV is a modest case of Grand Design, as the planet itself has not been made to resemble Earth - only the casting of roles speaks of Earth influence (or vice versa, as Omega got there first and may have influenced the way the New World colonies on our planet gained their independence). There's nothing modest about Miri, though, as terraforming in the UFP doesn't even involve doing pretty fjords yet, let alone whole continents: a century later, Gideon Seyetlik only did waterfalls...
Tracey's life expectancy was exactly the same as his firebox's power packs.
I doubt the Kohms would have been all that interested in killing the poor fella, who really didn't offer them anything extra dead, and
was observed helping them out while alive. More probably, once he ceased to be useful, he would have been sold to the Yangs. And who knows, perhaps he could have carved himself a niche in that group, too. Although probably not.
So what was the fate of the Exeter herself? Torpedoed and sunk in the gravity well of the planet's star? Dissected by Section 31 for the lethal biological agent? There's no sign of her being towed by the Enterprise as she departs, so what exactly happened? It would be terribly irresponsible to just let the ship's orbit decay and have her burn up to rain the planet with toxic debris.
Decay probably wouldn't happen: the orbit had been stable for six months already, so it wasn't one of those dangerously short-lived ones. Just let the ship sit there for a couple more years as Starfleet ponders whether it needs the hull or the scrap metal or just a practice target.
Then again, Starfleet does blow up plague ships in TNG. Kirk could have fired a torpedo when we weren't looking.
What fascinates me here is Starfleet operating practices. Two starships happen to visit this same planet for some reason, left unexplained - Kirk certainly isn't hunting for the missing
Exeter, has not heard of any trouble regarding her, and is surprised to stumble onto her here. OTOH, he does know that Tracey's ship was "patrolling in the area". Why doesn't Kirk get exact information on what another starship is doing in his current area of operations? Why does Starfleet allow its resources to be wasted by having two ships visit Omega IV wholly independently of each other? Is there a general Klingon scare going on, and Starfleet wants to randomize its raids against primitive worlds that might have fallen under the influence of Klingon agents, "Friday's Child" or "A Private Little War" style? Or does Starfleet simply launch out "The Hundred", expecting most of them to perish and a couple of them to eventually return with useful results, and thus not minding any futile "plans"?
Timo Saloniemi