I suspect reasons are that the technology is still evolving rapidly (hence products become outdated rapidly) and the uniform standards needed to make such a product work well for a large and diverse market are not fully in place yet. Give it time. In the meantime, there are many cost effective and robust options for those motivated to put their own music server together. The Logitech Squeeze system is the one I am most familiar with and can recommend. A fair degree of computer literacy and motivation is recommended before undertaking though still. Music servers are great when they work but there are still many snafus that can come up and make things things head south. Dealing with Terabytes of data fast and reliably is always a challenge.