From Memory Alpha:
"It was just a great episode of Star Trek. That's one I look at fondly." Braga further commented, "For a Star Trek episode to work, like 'Dear Doctor', it's gotta have a conceptual hook that's fresh, it's gotta have some sort of moral spine, and something that engages all the characters, most of the characters, in some interesting way. And if you look at that one, everyone's got a moment […] I thought 'Dear Doctor' was by far the best episode of the season. And it was very specific to Enterprise […] It dealt with a real issue. It had it all. It was charming, it was funny, it was well-paced, it had a good framing device, and it ended up […] dealing with a really good issue you'd never seen dealt with before.
All of these points could even be correct. The only thing it doesn't do is send a message I can live with instead of 'It's OK to let these people die out since 'evolution' has destined them to' (disregarding the goal-driven description of evolution here). I may be an aging, foolish lover of classical trek, but to me, them arriving at the morally 'right' conclusion is an integral element of Trek, and this wasn't it. For which I vehemently disagree with the follow-up:
That's Star Trek at its best […] I wish they'd all been 'Dear Doctor's that first season."