Lots of infrastructure for developers (Github, Launchpad, Jira and other Atlassian stuff, Basecamp, Trello,…) is not free software. Much of the non-free software that people want to use (things like Stack Exchange or Twitter, for example) have free software alternatives (AskBot or pump.io) which are not quite feature-comparable or don’t have a critical mass of participants to get the social benefits.
In general, I have always held the view that if you want to be a community project, then community members should be able to participate in all aspects of the project, including maintaining, hosting & monitoring infrastructure. However, this isn’t always the easy option. The free software alternatives are missing features, have warts and corners that you keep bumping off, and I have gotten push-back that we’re forcing tools which are not the best available down developer’s throats. In some sense, this is the classic idealist vs pragmatist debate.
In another sense, I still remember Microsoft, Sun/Oracle, Bitkeeper, Sourceforge, Google and others disappointing when the markets or business leaders forced them to cut services or make money. Using free/open source tools is a hedge against future corporate wind changes. So I see the decision to use free infrastructure as a pragmatic one.
Still, I see both sides - so it seems like there might be a good discussion about this - should free software projects have a strong preference for free software toolchains?