A lot of my favorite characters have been killed off in TV shows and books before.
As for ST, I'd say all
of my favourites have been killed off: Spock, Data, Jadzia, Janeway, Trip, and a few favourite background characters in the novels.
In the wider SF media: Robin, Golden Eagle, Martin in "V: The Series", Superman...
Traumatic at the time, refreshing for the main story, and bittersweet when/if they return.
And unfortunately I must admit that I often become nasty when I'm angry and frustrated.
get help for that.
Why not try writing your "nasty" post, but then clean it up by putting a more positive swing to it - and clicking "Submit Reply" only after you've removed any nastiness. If you're feeling hurt, don't inflict hurt back onto others.
You really can be in control of what you say online. And you might find your attitude in real life becomes generally more positive.
they could have demoted her...
You know what people would have said, "Finally, they promoted a major, ongoing female character into the Admiralty and what do the idiot novelists do? Demote her!"