Thanks for link Inactive Digital.
To me the apparently free element may be the most popular part, people who only have VM Broadband using it to get better picture quality and streaming onto their 2nd and 3rd (etc) televisions. I don't see many taking up the bolt-ons, unless they use it on their main TV.
I suppose keeping it purposefully niche VM can test their systems, and switch over TV360 customers to IP once they are happy they can scale it, and it's suitably reliable. A continuing test under the guise of a different product.