I don't want to stop browsing /pol/ because I want to have my finger on the pulse of the world at all times, but I don't want to be psychically assaulted with all the porn and the gore and the like. How can I hide all images and videos by default?

You should be able to just block i.4cdn.org with ublock or your hosts file

>>1534245 (OP)
You can install the browser extension 4chanx and set the mode to "Werk Tyme" (Work Time) to not show any media. (or do the opposite and only show posts that have media)
It's way more useful than that (filtering for example), and you can turn it on and off at any time.

On firefox you set permissions.default.image to 2 in about:config

>>1534245 (OP)
use 4chan-x