Ugh. You consider Dear Doctor a great episode?
It's not even a good episode. It's one of the worst examples of Trek combining bad science with horribly bad ethics.
Well... I did have to pick from Enterprise, it wasn't exactly easy to find a good one. But no, I think DD is notable for having a coherent argument for the Prime Directive in it. Often in TOS and TNG the PD was treated more like a burden, or a bad idea, or something to find loopholes in or deny directly. It was nice to be shown that, yeah, when you go out there you really can fuck shit up.
Actually it was the opposite... It didn't present any sort of good argument for the Prime Directive, and presented an example of people using an idiotic version of PD (which did not even exist!) in other to justify mass murder (that's what you're doing by withholding a cure to a bunch of mortally ill people)

If ever there was an episode that showed PD as complete crap, that's the one.
It's also another example of Trek writers knowing nothing about evolution. They just love to use that word, 'evolution', and every time they use it, they screw it up totally.
I could go on about all the things that are wrong with this episode, as I've already done a few times on various threads - from the many plotholes and illogical behavior by everyone, the inconsistency regarding the nature and sentience of holograms (one of the major themes of the show in general), to the casual racism towards Cardassians by a couple of regulars that is presented as being justified (something I don't remember a Trek show ever doing at any other time), to the hypocrisy and the one-sided arguments and a lack of mention of unethical medical experiments on humans throughout real life human history (all they could come up with was the Moset hologram mentioning humans conducting experiments on lower animals)...but I don't want to derail the thread.
It's one of those episodes that aim to be important and deep and thought-provoking and deal with a serious issue, but end up doing it in all the wrong ways and being incredibly shallow and hypocritical, not to mention full of illogical moments, out of character behavior and inconsistencies that come from manipulating the viewer and skewing the story in order to spoon-feed 'the message' to the viewer. If you actually start thinking about the events in the episode, it all falls like a house of cards. I remember starting to watch it expecting it to be great, and getting more and more bothered and pissed off with every scene.
I feel pretty much the same way. I remember when I first saw the episode, I kind of liked it up until Torres said this....
"Hologram or not, he's Cardassian. As far as I'm concerned, they're all cold-blooded killers"
At that point I literally facepalmed and thought "ARE YOU F#@KING KIDDING ME?!"
Actually, this ep is one of the few times the Maquis members like B'Elanna are used realistically. That is, these aren't highly idealistic Starfleet people -- they're regular folks who have definite prejudices toward the Cardassians because of their experiences fighting them.
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And being a regular folk includes being a complete idiot? It's not a Cardassian, it's a freaking HOLOGRAM, for crying out loud! A hologram created by the Doctor!
But if 'realistic' portrayal of B'Elanna is that she is an idiot, why is the Doctor and everyone else being an idiot? Why all the fuss over B'Elanna refusing treatment only because the Doctor is using an assistant with a Cardassian appearance - when the whole thing could have been solved by a simple "Computer, change parameters to: Human"?!
It gets even stupider when it's revealed what Moset did on Bajor, and B'Elanna, on hearing it, says "So I was right". Um, right about what? B'Elanna knew nothing about Moset and her problem with the hologram wasn't that he looked like Moset, it was that he looked Cardassian! What was B'Elanna right about? That all Cardassians are evil? That anything that looks like a Cardassian, even it's a hologram, is evil?

And this complete lack of logic is not mentioned by anyone. Normally when you see a person with racial prejudice on a Trek show, the show calls them upon it, you don't get the impression that the episode is presenting their views as justified and right.
The most baffling thing of all is that everyone in the episode keeps treating the hologram as if it was Crell Moset himself - and the episode itself seems unable to make the distinction, so it has the hologram say and do things that are supposed to make him seem like Moset to the audience... which makes NO SENSE, since it's just a HOLOGRAM CREATED BY THE DOCTOR from the partial data in Starfleet's records - and obviously he liked what he saw in those records enough to decide to use it as a basis for his assistant. So if the hologram is non-sentient, you have nobody to blame but its creator (i.e. the Doctor) if the hologram falls short of your ethical standards. And if the hologram is sentient (which, incidentally, would make the Doctor a murderer since he erased him at the end of the episode), there's still absolutely no reason for him to be anything like the real Moset, beyond the meager data about his personality from the Starfleet records. I suppose if Lewis Zimmerman was to kill or rape someone on Earth, they'd arrest the Doctor immediately?

And heck, the Doctor actually has more to do with Zimmerman than the Moset hologram has with Moset, since Zimmerman actually created the Doctor - and we still see over and over again that the Doctor is his own person and very different from Zimmerman!