You are mistaken. The tricks they used to get OOXML standardized[1] leave no room for doubt that they have been intentionally making interoperability harder.
You've linked to Wikipedia but there is no evidence there supporting your claim. In fact the criticism section includes pro-ODF supporters claiming the exact opposite:
> The ODF Alliance UK Action Group has stated that [...] the Office Open XML file-format is heavily based on Microsoft's own Office applications and is thus not vendor-neutral
If you've ever seen the specs for the old, binary office formats (they can be obtained) then you'd know that they are very complex indeed and that their OOXML siblings are pretty much direct encodings of the same data structures with some adaptations for the limits of XML. There is no credit to the argument that Microsoft deliberately made the OOXML office formats complex compared with the existing binary formats.
It's true that Microsoft pushed hard to get OOXML through the ISO, but the reason for that is clear: they wanted an open standard that was 100% compatible with existing Office documents. Something like ODF which lacks many of the features of Office would not do. It also makes their developer's lives a lot easier if they can specify a standard which describes their software's current behaviour. This is exactly what what Adobe did with the PDF ISO standard (1000+ pages) and nobody complains about that.
You are replying to a claim I did not make, that OOXML was not based on Microsoft Office XML or that the XML formats were made more complex than the binary formats.
> The ODF Alliance UK Action Group has stated that [...] the Office Open XML file-format is heavily based on Microsoft's own Office applications and is thus not vendor-neutral
If you've ever seen the specs for the old, binary office formats (they can be obtained) then you'd know that they are very complex indeed and that their OOXML siblings are pretty much direct encodings of the same data structures with some adaptations for the limits of XML. There is no credit to the argument that Microsoft deliberately made the OOXML office formats complex compared with the existing binary formats.
It's true that Microsoft pushed hard to get OOXML through the ISO, but the reason for that is clear: they wanted an open standard that was 100% compatible with existing Office documents. Something like ODF which lacks many of the features of Office would not do. It also makes their developer's lives a lot easier if they can specify a standard which describes their software's current behaviour. This is exactly what what Adobe did with the PDF ISO standard (1000+ pages) and nobody complains about that.