This is an interesting choice, given HTC's marketing of premium audio as a key feature of the HTC One X, One S, and One V. Additionally, HTC recently announced its plans to purchase the MOG streaming music service, which left many wondering if HTC would rebrand it with Beats, as well.
In any case, only one out of the four HTC devices I've owned in my life came with headphones of any kind, so I'm not really surprised that HTC made this decision. It still would have been nice, though.
[CNET]