In my opinion decent wordprocessor can't be written by single developer. We have four options:

1) take some old code (and pay authors)
PROS: huge amount of code is already written
CONS: no mui, large amount of money required
2) Scriba
PROS: mui, seems progressing, using typical MorphOS components
CONS: definetely premature, prebeta state, German docs :), gui
3) CinnamonWriter
PROS: seems progressing
CONS: own gui (no mui)
4) LibreOffice
PROS: it's Libre Office, Nadir has working build system :)
CONS: port all dependiences

I vote for Libre Office :)