Comment by kvb

I don't think commercial vs. open source really affects that much - regardless of open-source-ness, different projects are run in different ways. Just to give two examples, surely Office's switch to the Ribbon (and putting Office Apps online) was more speculative (or disruptive, or innovative, or whatever you want to call it) than anything being done by the open source office suites. Likewise, Visual Studio 2010 represented a big break from the past with a switch to many managed APIs driving their extensibility story (including the move to WPF for their UI), which was a huge change from their existing COM APIs.

Not all commercial projects are run like Windows, and it seems to me that most of their conservatism doesn't come from lazy or shoddy or shortsighted developers and managers, but rather their large number of hardware and software partners who take dependencies on undocumented implementation details (see Raymond Chen's blog for a virtually infinite supply of such anecdotes).