Word doc on the other hand is closed, with Microsoft not releasing the spec. In general, to open a Word file you have to have Word ($229 for the new user price) and it's only available for Windows and Mac. Granted, Microsoft does have a free Word Viewer, but I've never seen anyone use this.
I guess this is a good sign of how successful Microsoft has been in getting people so used to their software, that they think it's a superior format. Give schools the software at dirt cheap prices, get people to use it starting in kindergarten, and then that's all they know . . .