> Also, printing in 2021? I get that people still print, but it seems equivalent to improving the Fax dialog in 2006.
Free coloring pages (like: outlines of characters or whatever, you can easily find these with image searches) for your kids.
Worksheets for homeschooling or school supplementation, or if you're a teacher.
DMing RPGs if you want more than one screen of stuff visible at a time, or are trying to avoid screens at the table. I find, especially, printing relevant monsters or character sheets for likely combat encounters in a session to be super useful—saves you flipping back and forth between a bunch of things on a screen or doing the work of condensing stats, you can underline and notate one or two spells on the sheet so you're not searching at the table for "what would this magic-wielding creature probably cast first in combat with this party?", for a repeat-encounter big nemesis that the party comes to hate you can let the party rip up the sheet when they finally dispense with them, that sort of thing.
Most of the RPG stuff also applies to serious study or working-with-references. Screens still aren't a replacement for 20 sheets of print-out paper that I can have spread out on my desk all at once, and fold, write on, stick in a desk drawer for later, cram in my pocket, flip over to sketch something on the back, whatever.