Have the option to make page numbers as words (one, two, three).
Make it possible to add page numbers as words (one, two, three) as opposed to just numbers and roman numerals.
Also make it possible to integrate this with things such as the Table of Contents feature.
Who would want to use that? That's why numbers were created. To not have to write long words all the time.
Reading numbers from 20 written in letters is practically a twist for your brain. Supposing your documents won't have many pages, you could place them manually.