Did other shows have issues like that? I think Kess from Voyager hated the show and that's why they wrote her off.
She hated the Ocampan prosthetics due to allergies. That's why she suddenly acquired a vastly different hairstyle in Season 3, so it would hide her ears and she wouldn't need the prosthetics. The in-story reason is that because Ocampans only live for 9 years, she was no longer the equivalent of a 20-something human.
As for why she was written off the show... there are stories that float around fandom and who knows what the exact truth is, but the common denominator is the idea that due to hiring Jeri Ryan, they would have to fire someone else to maintain the budget. They had intended to fire Garrett Wang (Harry) since he had a habit of unprofessional behavior on the set, but then he turned up on some pop culture list of "America's 50 Most Beautiful People" and the showrunners thought they might lose female viewers in the all-important young adult advertising demographic. So they decided to fire Jennifer Lien, and going by how she's trashed her life since, she didn't take it well. Wang has been on the convention circuit for the past 20 years and has done reasonably well, though I can't think of anything he's acted in professionally since.
Even the
human characters do some good work portraying the different dimensions of human culture.
@Valka D'Ur might be mad at me for saying this, but as much as I despise Keiko O'Brien, she was useful for displaying how varied cultures can be between people from the same planet.
Keiko had exactly one good episode: the one where she faced down Vedek Winn over the school issue. I didn't like her in TNG, nor did I like her in DS9, for the most part. Yes, she was mostly supportive of her husband when it counted, but she could also be very whiny.
Wait...there's something wrong with eye candy?
As long as you understand that it works both ways. Some of the Trek series had attractive male guest stars. That's why I'm able to sit through some of the first-season TNG episodes everyone else seems to hate.
But when I finally watched the whole series all the way through years later... courtesy of DVR... I was going through the end/culmination of a particularly challenging time in my life and just finally starting my career after things being on hold for many years... so the theme song really resonated with me. So it had a special place in my heart. VOY had a similar resonance for similar reasons...
When I first heard the Enterprise theme song, I wondered if Scott Bakula was the singer (he is actually not a bad singer). But as for the song itself... bleah.
I love Voyager's theme, though. It's the best of all the series.