OOXML -- What's Happening Here?

Lucky me, I'm a voting member of of INCITS-V1 -- the sleepy standards group that has been working on such arcane things as TopicMaps. We're now working through the 6k+ pages of DIS29500 -- Microsoft's proposed standard for Office Open XML (OOXML). And my first question is, why?

Now, I'm not invested in or in any way partisan to the so-called-competing Open Document Format (ODF) that is already a standard and is in the process of getting a new version standardized. ODF is a part of the open-office software suite. I only just recently learned that it existed at all.

And, by the way, I don't see this (as some apparently do) as a Microsoft v. IBM fight, though I do see it as a fight of some kind. For me, a "standard" should serve a couple of purposes: to promote interoperability and to enhance portability being chief among these.

So, why do we need two competing open document standards? The answer from the proponents of OOXML is that there is no way to augment ODF (the extant standard) to include the features of OOXML. This is partly because OOXML supports the Microsoft Office binary formats (from Office 97 forward, I think) and partly because "the process model is different".

I'm trying hard to understand this. If OOXML can only be implemented with knowledge of the internals of various versions Microsoft's office serialization formats, how does that promote either portability or interoperability, except, maybe, within Microsoft's product lines. And I just don't get the "different process models" response -- I would have though that a standard, especially an XML-based standard, would be above that.

To me at least, the issue is more subtle. If we (V1) approve OOXML as a standard and it fails to pass the litmus test of promoting portability and interoperability, I think we weaken our standards process as a whole, making standards less trustworthy. Kind of like what's happened to Wikipedia; a phenomenal web resource that has been co-opted by corporate marketing efforts (try searching for "Windows").