Openness for me is first and foremost ideological, not practical, and certainly not just about the results. It's really about power, and the relationship between those who make the technology and those who are dependent on the technology.
Being dependent on proprietary technology whose continued existence is completely tied to the financial well-being of a single corporate entity is not a very good situation to be in for anybody, since it means that you are by proxy dependent on that entity and its success. Openness does not reduce dependency on technology, but it does reduce dependency on specific technology providers, and ultimately I think that's in my best interest.