No, it is because the do not want to know. The costs of moving the whole industry to OpenOffice and hiring Linux gurus to babysit it are just too high.
Why do you hope that this has nothing to do with Maemo. Its an additional choice. And having such a big company and more importantly a big office productivity app on Maemo will only make Maemo more important in the market. Do you not want that ? Or do you want Maemo to have apps like iFart only ? And if you do not want MS Office on your tablet, I am sure you will be free not to install it.
They're maemo and MeeGo... "Meamo!" sounds like what Zorro would say to catherine zeta jones... after she slaps him for looking at her dirtily...