I agree that genesis represents a moral dilemma about terraforming in SCI FI but TWOK doesn't really delve deeply into the moral dilemma, it's just an obstacle. it does comment on questioning leadership, through khan ignoring pleas of his 2nd in command. But it is mainly a bad guy revenge plot.
I do agree that TVH is hammy, and certainly less Star Trek then TWOK. While it is mainly a comedy it delves more deeply into environmetal ethics, even though TWOK could have done the same but didn't.
TUC was appears to be an allegory for the political situation of the time. It mirrors the Cold War and the differing of people at the time. And in the grand tradition of Star Trek depicts two different cultures finding a way to exist together, like how so many different people could work together on the enterprise in TOS
I think you missed a lot about Star Trek II, quite frankly, if this is all you got out of it. The film delves PLENTY deep into the dilemma over Genesis. Here is a device and a technology with the capability of transforming entire dead worlds into planets teeming with life and opportunity. The possibilities for improving the galaxy are endless. In the beginning, you see the scientists in charge of the project and how careful they are about the need to sustain life and not disrupt evolution on any potential life-generating planet (there can't be so much as a microbe). Later, you see the conflicting ideology between the civilians and their perception of the dangers of being in bed with the "military" (hey...is Starfleet a
military? We should engage in a thoughtful discussion on this one) on the project. Later, we see the triad engaged in a very lively debate about the "moral implications" of developing such a device, given that it could be used to destroy the populations and eco systems of entire planets in "favor of its new matrix." And ultimately, the very first deployment of the devise is as a weapon "in the wrong hands."
If that's not a Star Trek moral and ethical dilemma...I'm not sure what exactly you're looking for.
To say the only other element that isn't action/revenge driven in the film is Khan's henchman questioning authority makes me wonder if you've actually seen the movie in the last 20 years, quite frankly.
There is a massive character arc for Kirk filled with heavy themes that we never saw again portrayed as well in Trek...probably an even better arc than what was presented in TMP. Kirk is dealing with mid-life ennui and depression. He's surrounded by younger and optimistic cadets (just like in today's workforce where there are tons of people of the Baby Boomer generation starting to learn how to deal with the massive influx of Millennials) and this makes the situation even more pronounced. It takes his two best friends to open his eyes to how his "best destiny" is commanding a starship...and it takes the unfortunate crisis to initiate the change.
Moreover, Kirk is confronted with his own past and his life choices. The re-appearance of Carol and David has shaken Kirk to the core. We learn that he now even further questions his life and the decisions he's made / path he's followed. This, combined with the resurfacing of Khan, causes Kirk to examine his past decisions and choices in a way that really defines the character.
Finally, there is the Spock sacrifice. This brings Spock's arc established in TMP and brings it to its full conclusion. Enough has been written about this where I don't feel the need to pontificate. Suffice it to say, this provides the audience with the insight into the fact that Spock's soul truly has become the most "human." It also brings Kirk's arc to a climax, as he admits that he's never faced death like this, and has spent his life laughing at danger because he's been more lucky than good. It's the most humanizing element for both Kirk and Spock in the entire franchise.
I also totally disagree with what you said about TUC. No shit it's an "allegory for the end of the Cold War," but it's done so obviously and without any finesse that it's not NEARLY as effective as the deeper themes explored in TWOK. What you see as a "grand" illustration of two cultures learning to work together (to do what, BTW, prove they can collaborate on an assassination attempt), I see as a pretty mundane outing. Compare Kirk's closing statements/revelations in TWOK ("I've cheated death" and "young...I feel young") with his closing statements in TUC ("people can be very frightened of change" and "once again we've saved civilization as we know it") and I clearly see that TWOK is a senior thesis paper while TUC is a Sophomore frat party. Sophomore frat parties can be fun (and TUC was fun), but they're not to be mistaken for anything deeper. The stuff in TUC is hand-waving and surface material. Kirk's prejudice arc is not nearly as emotional or "adultly portrayed" as the arc he goes through in TWOK. "Hey, now I know how prejudiced I really was." Ok??
TUC was a light and obvious allegory, basically in the same category as "Let That Be Your Last Battlefield" while TWOK was a taught thriller with very subtle in interconnected themes and character explorations, similar to the classic "Balance of Terror."
TUC also has an equally sophomoric villain compared to Khan. Khan is truly a menace from Kirk's past. He has fought to keep his people alive in a nightmarish hell for 15 years. He is a man of tremendous (engineered!) ego. This combination, plus the growing resentment for Kirk (not for leaving him there, but for never caring to follow-up) has driven him mad. He throws his entire life away, and the lives of the people he fought so hard to protect, just to attempt to kill Kirk. Chang, on the other hand, just doesn't like peace. He's a cold warrior (or something) who twirls his moustache, apparently doubles as a legal prosecutor, and pretentiously quotes Shakespeare. No depth. He just "doesn't like change" and he's going to further an inane plot to continuously assassinate whatever leaders in his government continue to push the peace process forward because he'd rather die than live in peace with the Federation. Which makes.....NO sense given that the Klingons have pently of other challenges and enemies to motivate them throughout the galaxy.
I guess the difference is in the preference for the way these themes are presented. If you want them interwoven masterfully into a tense and action filled story, then TWOK is for you. If you want them obvious and laid-out for you (like a TNG Picard speech or Ready Room scene filled with lame exposition), then TVH and TUC hit the mark perfectly. I for one prefer Star Trek when the message is subtle but powerful, not overt and ham-fisted.
But hey man, to each their own.
