Gremlin sez, "Sonos recently pushed an update to their once stellar music system which disabled windows DRM. They decided that it was unnecessary to continue to support this feature moving forward. Unfortunately they also pushed this update without warning to many customers, and they are offering no way for those customers to roll back to the previous version. Their answer to those customers effected is that they've made the decision for us. Many customers have been complaining, but it sets a dangerous precedent for them to be able to remove features at will. Today it's a lightly used DRM system (mostly it effects people using Zune Pass at this point) tomorrow maybe it'll be Sirius Satellite, spotify, or something else more people use. We've suggested that we'd be fine with them allowing us to roll back and making the decision ourselves to not take future update but they will not allow this to occur."
It's entirely possible that the decision wasn't Sonos's to make. After all, DRM license agreements routinely provide for "revocation" in which a DRM vendor or licensing body reserves the right to order its partners to discontinue the playback of its DRM for some reason or another. Which is one of the great dangers of DRM: you buy a device with six features today, and tomorrow it has five, or four, or three, or none. The negotiations resulting in these confiscations are confidential, conducted between giant corporations without any input from the people who've bought the equipment and the media to play on it.
I wrote a long, open letter to Wired editor Chris Anderson about this in 1994, when he told me that rejecting DRM was "idealistic" and defended taking a "pragmatic stance" when reviewing technology that had DRM in it. But worrying about what happens when your devices are designed to be remotely deactivated without your consent or knowledge is eminently pragmatic and has nothing to do with idealism, as we keep on learning.