It was a huge loss of status for Majel. She went from playing a serious officer in charge when Pike is gone, to a sad "old maid" character whose main feature is a crush on someone who wants nothing to do with her.
Add to that, her backstory that came along in "What are Little Girls Made Of?" renders the girlish Spock crush less plausible.
It was a symptom of two things: Nurse Chapel being shoehorned into the show because the producer's mistress wanted a job, and the broader problem of Star Trek having writers who were not good at writing female characters.
Or maybe they weren't allowed to be good at it. After NBC didn't like Majel in the role of Number One, apparently Gene lied to spare her feelings, telling her that the network wouldn't allow a woman in an authority role. Then he had to tell a lot of other people that story because Majel interacts with them. Then the fable took on a flattering aspect: Gene the feminist hero versus NBC the chauvinist wet blanket.
And in any case, in order to maintain the story that spared Majel's feelings, from then on Star Trek had to keep all Starfleet women in humble positions. Barbara Stanwyck was the honcho and very popular on an Old West show, The Big Valley. But in the sci-fi future, girls will be aboard to take notes and fetch coffee.
When you think about it, the whole Majel subterfuge was a wrong turn that hurt Star Trek a lot. Gene should have just been honest with his girlfriend for the good of the show.