"The Cage" always seemed dull and bland to me. "Where No Man Has Gone Before" always seems exciting and energetic.
I think it was a dreadful idea to introduce Captain Pike in a depressed state, questioning his place in the universe. Do that kind of thing once you've established the character (see: Kirk in Star Trek Beyond), otherwise it just comes across as if the captain doesn't want to be there.
True.
"The Cage" was a dramatic nonstarter story because Pike is never once tempted by the Talosian illusions because he knows it's all a fake and he's being manipulated. Since there was never really any choice the story is merely about escape. WNMHGB on the other hand puts Kirk in a tremendous personal dilemma of his own making. He decides to probe out in the unknown and ends up losing crew, crippling his ship and mutating an old friend and he spends the rest of the show trying to deal with that. More than mere action that is what sold the show.
Clearly.
Unlike
"The Cage"--with its lack of a true moral dilemma for the lead characters, WNMHGB hurled the new captain into a situation he could not deny or walk away from--he was obligated to deal with a situation where there would only be tragic consequences as a solution. He is repeatedly tested as a captain
and human, struggling to decide which side's call he would answer. This made Kirk a well-realized character who felt
real, a human compelling as a feeling hero--not a cardboard "leader", but a person we would want to follow every week because he grounded the science fiction in human terms. We wanted to see how he--not random leader/lead actor, but how Kirk faced problems and the unknown.
The action element was minimal in screen time, but it served its purpose, as part of the conclusion, as opposed to
"The Cage", where there were set pieces (the fight on Rigel, the crew's attempts to rescue Pike, etc.), which had not true bearing on character development or the outcome of the story.
Concepts of judgement over who has the right to take or preserve life, starting Kirk's tradition of tearing down
anyone pretending to be God, loyalty--the
"command and compassion" which Mitchell sums up as
"a fool's mixture", not only illustrated what kind of being
he turned into, but how Kirk was not a ends-justifies-the-means cutthroat. His values were caught between the frigid, alien pragmatism of Spock ("
kill Mitchell while you still can") and Mitchell wanting to force this inevitability, only so he would finally exercise his "place" as a self-identified "god" who would do what Kirk fought against until the last minute.
Even as Mitchell met his end, he was still a sympathetic antagonist (unlike the Talosians, who were confused / surprised that humans did not like to be enslaved, then washed their hands of their part in the affair), as he--as pointed out by Kirk--
"...did not ask for what happened to him." There are near-endless reasons why WNMHGB is the greater pilot (of the entire franchise), but at the end of it all, there's no question why it perfectly set the characters, dramatic/format standards for all that
Star Trek was and could be as a series and sci-fi concept / property.
"The Cage" was incapable of doing that, which is why it was better served framed by the plot of
"The Menagerie" 2-parter; it needed
real Star Trek--the WNMHGB-launched
Star Trek to tell this bygone story that would not work as a standalone story.