Maybe I'm misunderstanding, but are you arguing that it's
better for battery life that you stream music (presumably over a cellular connection) until you get home and download it rather than downloading whatever music you want to listen to once and then playing it back locally?
Because I'm pretty sure the former means your cellular radio is on constantly, eating into your battery, while the latter means its on only while downloading whatever you want to listen to and it's off/in a low power state otherwise