Just because you labour for free does not mean your content cannot and is not usurped for commercial purposes.  Wikimedia content is intentionally created with the intention of allowing and encouraging commercial repurposing of it.  This is not really an emerging trend either, but one that has been going on since at least 2000 or so when AOL and other online service providers usurped fan communities, developed relationships with officially licensed content producers to host non-paid fan labour under their auspices.  

There are issues at play here that are probably important, but they speak to larger issues regarding the state of employment in the United States where people are expected to labour for free as an internship. I believe in the USA there was high level litigation regarding this labour related issue.   http://www.theatlantic.com/business/archive/2013/06/the-court-ruling-that-could-end-unpaid-internships-for-good/276795/ has some details but I have not followed up much on it since.