Microsoft New Zealand representative wants competitors to make reverse engineering over their products. Standardizing the whole format would not permit Microsoft to have a 'competitive' advantage.
Here is what he says in ComputerWorld:
Why does OOXML not include macros, scripting, OLE serialisation, and leave so much to be application-defined?
Competition between Office Automation suites has always been an important factor in driving much of the innovation that we enjoy in the industry and as users today. The process to standardise OOXML is a process to standardise the data format, not an application. Standardising the full application would remove the ability for different office applications to compete with each other and slow that pace of innovation.
Sorry, but the macros are stored in a file format, so not defining how to interpret this data will lead to a competitive advantage for the company of Redmond, and will be a killer for interoperability. I don't want to buy a Windows license and an Intel PC just to be able to decode their crappy format.