Ah, nothing like a good 'ol Trekkie ethical dilemma for our heroes to solve.
Dear Doctor is the first episode of ENT that asks questions outside of "how are our heroes going to blow up the bad guys this episode?". Going into it, I was excited. Mainly because this was the first episode to present a puzzle for the characters to solve through their ethics and morals.
Unfortunately, I think they handled it all wrong. The episode asks some interesting questions and had a good premise behind it, would've made for a great TNG episode, but the solution is downright pitiful. We can all tell the episode is here to provide some kind of backstory to the Prime Directive, it's spoon-fed to the audience with a few lines of dialogue, but it compiles all the worst aspects of the Prime Directive and combines them together for the story of this show.
I'll admit, I did feel they put out a convincing argument while watching it, but after doing a little more reading (mainly on evolution and Neanderthals, who were their shining examples of non-interference and their moral justification for letting a whole species die off), their whole logic is flawed. Evolution is not some magical solution to all problems nor does it make any moral distinctions. It's a process that carries out over many generations and allows a species to better adapt to their surroundings, not give one species an advantage over another. It is just the result of a species becoming better suited to their environment.
A generational disease that has the inevitability of wiping out an entire species of intelligent people is NOT a natural part of evolution. A life-threatening disease is not a natural part of a person's growth and evolution, it's a problem. Neanderthals were wiped out because humans were just smarter, physically better adapted to our environment and therefore better at acquiring essential resources.
This species is intelligent, is perfectly suited to its environment and even has its own space exploration technology. Letting them die off can't be justified in my mind, and the "playing God" argument is just as wrong as the act itself when you consider the doctor does exactly that. Phlox's role as a doctor is to save lives, it's what he is morally and ethically obligated to do, not take them. This, in my opinion, goes against everything he stands for.
Maybe these are the growing pains I previously spoke of (and hoped for) in seeing a pre-Kirk, pre-Spock Starfleet crew trying to survive out in the cold, dark, mysterious void they're out here exploring for the first time, but I can't help but feel somewhat insulted. The intent was nice, more ethical conundrums are welcome, but the execution was all wrong.