Hipster-hate strikes me as just another thinly veiled form of bullying, and it's interesting to see how readily internet nerds - the people who are disproportionately to have been bullied in the past - engage in it. Look! He's different! Let's make assumptions about his motivations and get him! It's also interesting to see how many times Reddit (and other communities) fly into a rage-fest because of lack of context,…
Author summarizes the rage quite well: "The reaction, then, had nothing to do with hipsters. It was a hatred of people that need to stand out for standing-out's sake. That realization was at once positive and negative—people didn't hate me because I was a hipster, they hated me because I looked like I was nakedly desperate for attention, and had gone about that attention-grabbing by glomming on to marginalized trends…
Based on my own anecdotal experience, I think part of the anger comes from a sense of discomfort at the dissonance between how one thinks the attention-seeker is being perceived and how one thinks the attention seeker believes they are being perceived.
In the case of someone using a typewriter, the issue isn't simply that one thinks that person looks foolish, it's the dissonance between knowing they look foolish and imagining that they think they look super cool. Dissonance leads to discomfort, discomfort leads to anger.
With other kinds of attention-seeking public behavior -- street performance, for example -- even if one doesn't enjoy it, there's a much closer match between how the performer believes themselves to be perceived and how they are actually perceived (assuming they are competent).
I harbor no ill-will towards hipsters, self-identified or otherwise. But if I imagine someone using a typewriter in Starbucks, it does make me uncomfortable, and by far the biggest part of that is imaging that person thinking they are really funny or really cool.