Office Open XML was only standardized in order to combat the threat posed by Open Document as organisations were starting to mandate use of standardized formats.

You write as if Microsoft did this because they wanted interoperability, when in reality they only begrudgingly accept that some must be allowed in order to avoid losing control of the market.

The real solution would have been to never approve the OOXML standard and not legitimize Microsoft’s attempt to make their proprietary format appear open.