This week, in a move little noticed outside the tech world, the music service Rdio unveiled a new design. During an event at South By Southwest, its designers described the new look using plainspoken language. The new Rdio is faster, they said. Simpler. And also: “more social.” But to me there was a more substantial point, unmentioned in their handsome Keynote slides. Rdio and services like it were undermining many of the reasons I had started blogging about music in the first place.