One attack vector doesn't need to cover everyone. Developing many attack vectors as possible gives you the greatest chance that one of them will work against a particular target.
As an example, lets say that a particular organization has taken a number of standard precautions to prevent audio from being recorded surreptitiously. They've banned cell phones and chosen computers without internal mics. The ability to record sound via the output jack would be huge.
Besides, I bet beats would work just fine. The reason Sennheiser's worked so well is probably because they have a large speaker, whereas a ear bud has a pretty small speaker. A speaker being used to pick up audio is basically a dynamic mic, which are not very sensitive for a given size. So I'd expect something like Beats, or the cheapo AKGs I have connected to my audio jack right now to work quite well.
As an example, lets say that a particular organization has taken a number of standard precautions to prevent audio from being recorded surreptitiously. They've banned cell phones and chosen computers without internal mics. The ability to record sound via the output jack would be huge.
Besides, I bet beats would work just fine. The reason Sennheiser's worked so well is probably because they have a large speaker, whereas a ear bud has a pretty small speaker. A speaker being used to pick up audio is basically a dynamic mic, which are not very sensitive for a given size. So I'd expect something like Beats, or the cheapo AKGs I have connected to my audio jack right now to work quite well.