TOS-era Trek is an interesting anomaly to me.
When it's good- "City on the Edge of Forever" or "Balance of Terror" good, it can rank amongst the best science fiction, bar none. Good TOS gets scripts written by legends like Harlan Ellison and Richard Matheson.
And when it's bad- we get "Spock's Brain".
TOS doesn't really get to have a middle zone, and that becomes a problem for some viewers. They treat the whole series like it's nothing but rubber rug monsters and Shatner overacting and they miss the message the series sent.
I disagree, classic Star Trek is no different from any other good series; it has outstanding episodes, horrible episodes and middle of the road episodes. All that has really changed is the style of TV, acting and length. The stories, when great, still hold up. A bad episode is a bad episode and there were PLENTY of latter day bad Trek episodes. And plenty of great and middling episodes as well.
Plomeek, don't bust a gut trying to love it. It's no crime if it doesn't light your fire. I give you a ton of credit for trying, for giving it a fair shake and for wanting to like it. But it's probably not your thing, and the style too divergent from your taste.
To give some perspective, I grew up with the original series, so I will never be tired of it or feel it's outdated or (god why do people use this word?) camp. I still wish I could throw haymakers like Kirk. TNG was great at the time, with some of the best acting TV has ever seen, but it's the series I revisit the least. It became boring for me as they dropped the adventure in favor of message drama, crummy B stories, techobabble and family squabbles. DS9 wound up being my favorite sequel series, as it focused on character and had some great and exciting arcs. Enterprise has totally grown on me, becoming a lot better now than it was when I first saw it. Voyager is just awful, but some episodes transcended the mediocrity of the people involved. But it was a rare thing.
So it's all a matter of taste. I appreciate the respect you're giving it, because no matter what one thinks of the show personally, it has well earned its place in pop culture history.