>I don't know what your position is at your job, but not everybody has the liberty of converting every document that crosses their desk. For some of us it's a relief just to be able to use LibreOffice, and if we were to constantly send back revisions to others' documents in a different "weird" format we'd likely piss off some of our co-workers. The last thing you want is for people to think of a Free office suite user as "that guy who keeps sending stuff in that wacko format"... right?
His point was that versions of MS Office which can read OOXML can *also* read ODF. Either way there is a conversion step, whether in saving to OOXML from LO or in loading ODF in Word, so in both cases if you need to be absolutely certain how it will render in Word, the only way to know is to open it in Word. Thus, there's no obvious benefit in being able to save in OOXML vs ODF.