I've been fortunate enough to not experience hostility for being out of the loop. Mainly because I simply keep quiet. Usually, when people find out, they just get excited that they tell someone about their interest without getting a "yeah, I already know" in response.
What counts as pop culture is different for everyone, so there is no reason to require someone to experience a piece of media. Getting angry at someone for being out of the loop is very irrational. After all, for every loop that they think they are in, there are infinitely more that they have no idea that they're out of.
Trying out mainstream stuff has value, but it should always be from a place of curiosity, never fear or obligation. I'd argue that experimenting is important, since I've learned the hard way that sticking to close to what's familiar can lead to some bad burnout.
As for Risk of Rain, my former roommate plays it occasionally. It's one of those XBOX games where you play as a group (or solo) and try to survive as long as you can. Sessions usually take a really long time for him, since he's super into competitive XBOX stuff. I can see its appeal, but its definitely not my cup of tea.
Out of all the media you mentioned in the OP, I've only really experienced Alladin, and Kurt's Smells Like Teen Spirit.