A mobile music platform only distracts the user and damage their hearings.
On the whole I have to agree but I think when students get to the age where they might want to be motivated by arduino, I would suggest that there are many who would understand the benefits of music. I personally listen to music quite a lot (obviously not at the volume level many kids listen to it at) but it can really make a difference in how you feel/how productive you are. So music in moderation (whether a portable device or not) can have major benefits.
On another note, I saw an elderly lady on a bus I was travelling on the other day listening to an ipod. You could tell she was happy listening to whatever it was and it was improving her mood. Travelling around on buses by yourself doesn't normally do good things to people's moods.