Parents are asked to buy books for their kids that are used once and then sold back for much less than what they bought it for. So I don't see what the big deal is in asking parents to purchase software that will last them several years that costs about the same as a single college textbook (if they get it discounted, as the article mentions). Asking parents to fork out $500 is unreasonable, but asking them to fork out $80 is not.
Speaking from experience, earlier versions of Office used to be just about as unreliable as OpenOffice. I, too, used to use OpenOffice, but mostly because it could export to PDF. Office 2007, however, is much much more reliable and I have never lost my work. OpenOffice still has issues with data loss.
Also, kids don't know that they have to save to Office 2007 format from OpenOffice. They'll save in the default OpenOffice format, and get yelled at by their instructors for not having the right version. They'll also get yelled at because of formatting issues. Whenever I converted between OpenOffice and Office 2003 I always had to edit my paper.