[robg]

I don't know why you got downvoted, because this is exactly the only reason I can see. Embedding these capabilities in an existing big brand provides both literal and figurative cover. People already love walking around wearing their Beats. Adding heart(Beats) makes alot of sense especially since music is designed to influence how we feel.

[zimpenfish]

This is the only thing that makes sense to me - Cook specifically said "getting people to wear something is hard" when talking about the wearables future and like you say, people are already wearing millions of pairs of Beats...

With optical pulse sensor and accelerometer for step counting, it's the easiest "slip personal health tracking under the rug" play there is.