Star Trek discussions do tend to be interesting.

Gene Roddenberry always tried to tuck a moral dilemna / lesson in every episode. Whacked you upside the head with a hammer sometimes too.

A good deal of why it did so well was writing talent. In TOS many of the episodes were written by some of the big named sci-fi writers of the day. In the later series' it was very obvious when a writers strike was under way.

I like that Star Trek raises the question, but the PD comes down an excuse for inaction unless we know the outcome of our actions for sure. It also suggests a cosmic plan fated to unfold, which people shouldn't intervene in.

The Star Trek Prime Directive Meets Ayn Rand thread was an excellent discussion.
In fact, I am watching Star Trek: The Next Generation as I write this.