This was always about booting h.264 from its position as the standard for publishing video on the web.
I have no faith that WebM is non-encumbered. The real issue is our patent system, not codecs.
I suspect that the real motivation of the H.264 supporters is that the patent encumbered codec will allow content providers and proprietary software vendors to control who is allowed to produce video playback software (at least, they could make it impossible for free software to support the codec), and impose mandatory content protection. That will make the content industry giants closer to their ultimate goal of eliminating all the culture they do not control.