A lot of the time it's a lot harder than that. Suppose you have government records stored in Word files and you can't use Office. How do you retrieve that many files? It would be a monumental effort to apply the correct formatting to hundreds of documents, and if things like "Track Changes" have been done, it would be even harder.
Picking a format you know you'll be able to read fifty years from now, even if it takes writing a piece of software for your shiny new quantum computers, is a lot nicer. Store files in the OpenDocument format and even if all of the OpenOffice and OASIS people are dead and the software long-gone, you'll be able to dig up a copy of the standard and write a program to extract all of the text.