Longhand rules because - it's low pressure (you know you still have to type it up sometime, but for now, that day is in the future so you can relax and compose a little.

Also because the act of writing longhand forces your thoughts to slow to the speed of your hand, allowing you to examine them more closely.

Also because it's endlessly mobile and you can do it anywhere without worrying about it being stolen or electrocuting you. It's amazingly low-tech and effective. I find that I work far better out in the world - in a bar, in the countryside, in the garden - than I do in my room. Its'because you're connected to the world and feel less lonely but also free to do your own thing.