I don't know that Garrett made a big deal of it. From what I heard, he suggested it to Berman or Braga, and they shut him down with that boneheaded line: "someone gotta be duh ensign". Ignoring the fact that every other recurring ensign on TOS, TNG, and DS9 was promoted.
That's typical for Berman and Braga. I get the impression that they had a very bossy attitude during the time they were in charge of Star Trek.
I'ts also been stated that Berman and Braga had creative discussions with their cast members. I get the impression that they did listen to suggestions from the cast members but there were only some of them who had any saying when it came to character development and such.
When it comes to Voyager, I'm sure that the only cast members who had any impact on the decision making were Mulgrew and Picardo.
Beltran and Wang were regarded as "troublemakers" and therefore constantly over-run by the bosses and the rest of them, even including Jeri Ryan despite her status as the "savior of the show" were simply ignored.
It was the letter writing fans and critics who made a big issue of it, I think. I still maintain that the scenes in "Unimatrix Zero", "Nightingale", and "Author, Author" were a middle finger to them. Why else highlight one of the story's worst inconsistencies?
Did fans of Kim take part in a letter campaign?

I've never heard of that. Do you have any details?
In that case, the fans of Kim should be eternally grateful that he wasn't turned into a soul-less, ugly disgusting monster and then killed off. Look what happened to Kes when people started to send in letters and suggestion for her return in the series!
He reportedly jumped at the chance to have his character turn out to be an alien, because it would have taken him in a new direction, like Nog on DS9.
If Nog had been on Voyager, he'd probably have been stuck busing tables and getting locked up for petty theft all seven seasons.
Or being demoted and sent down to be a member of The Torpedo And Shuttle Building Team!
is also possible. But I maintain that Janeway has an almost scary hold on her crew. Look at the end of "The 37's", and "Tuvix".
There are two possible scenarios here:
1. Janeway was very popular among the crew and seen as a smart, skilled captain who also cared a lot for each and every crew member. Therefore the crewmembers, both Starfleet and Maquis saw her as a great leader who they were ready to sacrifice themselves for and also never questioned her more dubious decisions.
2. Janeway ruled the ship with fear, just like Stalin. Tuvok was her Berija and the slightest questioning of any of her orders were reported to her with dire consequences for those who had expressed the slightest doubts of her decisions.
Those who were labeled as "unreliable" ended up in Cargo Bay One where they were constantly locked in and had to work day and night as members of The Shuttle And Torpedo Building Team. Or they simply just "disappeared".
Pick your choice!
Given that Kes has long been one of the Doctor's staunchest advocates, does it seem likely that they would come into conflict in this way? Since she didn't wear a uniform in the B&A timeline (Neelix, by comparison, did), she may have practiced medicine as a civilian, making chain of command less relevant.
OK, I just replied to a post by
Guy Gardener in another thread abou the events in
Before And After that they took place in an alternate universe and not "our Star Trek Universe".
But I still don't understand why Kes was always regarded as a "civilian" and not allowed to wear a Starfleet uniform when there were several Maquis who didn't have any Starfleet experience at all but still put in Starfleet uniforms. OK, neither Talax or Ocampa were members of the federation but if Neelix could show up in a uniform in beforew And after, why not Kes? In fact,she's the one non-Starfleet member who most easily could have been given the honor of becoming a full-time member of the Starfleet crew due to her ability to learn and develope.
As for Kes being one of the Doctor's staunchest advocates, I guess that's because she's a fan. I guess that he has been a musical influence to her.
KES: "As soon as I heard The Doctor play those wonderful tunes, I realized that music was my call, therefore I started my own band!"
I'm sorry, but I don't regard regaining an old rank as a real promotion. You believe one thing. I believe another. Let's leave it at that. As for Harry Kim . . . I suspect Janeway got whiff of his behavior in the Season 2 episode "Resolutions", even though Tuvok had promised to remain quiet about it.
I'm sure she did. Note my alternate scenario above in my reply to
Oddish when Janeway's authority over the crew members is debated.
His behavior then, his constant whining and almost crying every time a possible shortcut home turned out to be a false hope, his constant ability to be seriously injured, close to death or beaten up on several occasions plus his "awful taste in music", according to Janeway was the real reason that he was never promoted