You talk as if these "open" formats save the various formatting that you can do in MS Office. This discussion is mostly about the fact that they remove the formatting that you add to the document when it's saved into the XML format. The discussion isn't about backwards compatibility, it's about compatability with the formats being used today. If people only wanted to write text, they'd use WordPad, or Notepad, which save documents in text and html as well.
You talk as if these "open" formats save the various formatting that you can do in MS Office. This discussion is mostly about the fact that they remove the formatting that you add to the document when it's saved into the XML format. The discussion isn't about backwards compatibility, it's about compatability with the formats being used today. If people only wanted to write text, they'd use WordPad, or Notepad, which save documents in text and html as well.