"We could have used a format from others and shoehorned in functionality, but our design needs to be different because we have 400 million legacy users. Moving 400 million users to XML is a complex problem"

While it’s good news that Microsoft is defaulting to an open XML format in their next iteration of Office, Stephen O’Grady of RedMonk thinks that the company could have done better to also support the Open Document Format, an OASIS standard. O’Grady questions why the company chose to develop its own duplicate format, reasoning that lock-in could not have been the motive. He wrote, "similar to its Metro format, the new formats while not accepting outside contributions or guidance - and therefore not an open standard - can be considered by virtue of their documentation an open format. Lock-in then seems to be an inadequate answer." But Microsoft’s response, that the format is for ensuring backward compatibility for legacy users, while reasonable, still doesn’t hold water for O’Grady. He states; "The objections to such support typically run along the lines of Microsoft has never had to compete on implementation, why would they choose to start now?" His post goes on to counter this argument.