I think it boils down to lacking in writing. I used to watch shows that had a lot of political statements made through their worldbuilding and character interactions. These were good stories because to find a political message there you had to think about it and draw parallels yourself. More modern shows tent to just outright mention current political movements IRL or just straight up lecture people by characters doing speeches. It's very distracting because it clearly breaks away from the flow of the show. Even if the lecture is something I 100% on board with it may feel even worse because it feels like the show insults my intelligence.
It was less blatant. As another poster mentioned, the politics was part of the narrative. The GamerGate debacle was a big shifting point, where video games have become another cultural battlefield. I'm not picking on one side or the other, I just want to enjoy my video games in peace without people calling each other SJWs or racists or sexists.
Just as an example, there was a huge kerfuffle in Battlefield a few years ago because they added black and female playable characters. They proceeded to shove it in everyone's face so we could be in awe of how progressive they are, and then the counterparty threw a huge fit about how those people would not have been combatants in WWI. I don't particularly care either way about the change, because it doesn't impact my gameplay. I do care that for a while the entire community focused in on this one aspect that has almost nothing to do with the game itself. It makes me dislike both sides, because they're both getting in the way of the game.
They complained about Picard. I wasn’t allowed to watch it as a kid because my parents didn’t like the political agenda (my guess, though I’ve never asked them, is they thought it was communist/ anticaptitalist due to the absence of money).
Many modern US "conservatives" complain that Star Trek is political, and when it was Kirk and Picard it wasn't.
If you said that you didn't like Kirk, he's an unbelievable badly-written over-the-top Mary Sue character, noone would call you an anti-Semite because Shatner happens to be Jewish.