I print out academic papers so that I can highlight in different colors, write in the margins in different colors and to throw into a bag and read on public transport.

When I write papers, usually in collaboration with others, it is far easier to scribble in the margins, draw lines to reorganize sections, etc. And you get a better sense of how the paper will look once published.

and ... it is nice to have a break from staring at a screen and being able to sit on a couch, etc. Yes, I do use an iPad, but paper is nice. Interested to see how the new Amazon Kindle Scribe will feel when it is released, mind you it's only B&W.