If typing on a screen was really as enjoyable and productive as a keyboard, we wouldn't see the enormous collapse in long-form text blogging over the last decade in favor of just uploading images with a much smaller amount of text.

Physical keyboards appeal to, besides those who just like to write a lot of text, also people who often need to SSH into a server and enter extended characters, or who run Emacs on their phone and want to easily use the power of packages like org-mode.