Music is only passive entertainment if you just listen at it, not if you sing it, play it, or dance at it.For better or for worse, passive entertainment such as movies, books, TV shows, music, etc., is a large part of our popular culture.
Strictly speaking this is true, but people usually discuss the things they watch (or read, or listen to, etc.), with their friends or, with the advent of the Internet, even with random strangers. The shared narratives thus facilitate the "emotional intimacy" you speak about. Furthermore, some specific works of passive entertainment, as well as generalized common tropes, make up a huge chunk of the cultural context without which it would be difficult to communicate with anyone in our culture on an emotional level (as opposed to, say, presenting mathematical proofs or engineering schematics to each other).
I agree that people spend lots of time talking about these kind of things, and that the more shared topics of conversation you have with someone the easier it is to socialize with them, but I disagree that there are few non-technical things one can talk about other than what you get from passive entertainment. I seldom watch TV/films/sports, but I have plenty of non-technical things I can talk about with people -- parties we've been to, people we know, places we've visited, our tastes in food and drinks, unusual stuff that happened to us, what we've been doing lately, our plans for the near future, ranting about politics, conspiracy theories, the freakin' weather, whatever -- and I'd consider talking about some of these topic to build more ‘emotional intimacy’ than talking about some Hollywood movie or the Champions League or similar. (Also, I take exception to the apparent implication of the parenthetical at the end of the paragraph -- it is possible to entertain people by talking about STEM topics, if you're sufficiently Feynman-esque about that.)
For example, if you take a close look at various posts on this very site, you will find references to the genres of science fiction and fantasy, as well as media such as movies or anime, which the posters simply take for granted (sometimes too much so, IMO; f.ex., not everyone knows what "tsuyoku naritai" means right off the bat). A person who did not share this common social context would find it difficult to communicate with anyone here.
I have read very little of that kind of fiction, and still I haven't felt excluded by that in the slightest (well, except that one time when the latest HPMOR thread clogged up the top Discussion comments of the week when I hadn't read HPMOR yet, and the occasional Discussion threads about MLP -- but that's a small minority of the time).
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A list of some posts that are pretty awesome
I recommend the major sequences to everybody, but I realize how daunting they look at first. So for purposes of immediate gratification, the following posts are particularly interesting/illuminating/provocative and don't require any previous reading:
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