Most of this stuff was published a few months ago and completely debunked - the ip range was just chosen because it isn't routable.
The BTAgent is there to manage the devices - e.g. Updating them. Its possible that some stats are there to improve line quality as well. To me that seems a reasonable tradeoff, and if I wasn't happy with it then it is always possible to use your own piece of CPE.
The other point is that the interface that BTAgent runs on isn't exposed to the internet, it is only available from the management network so someone obtaining the keys for BTAgent would also have to compromise the management network - at which point bt has bigger problems!
The BTAgent is there to manage the devices - e.g. Updating them. Its possible that some stats are there to improve line quality as well. To me that seems a reasonable tradeoff, and if I wasn't happy with it then it is always possible to use your own piece of CPE.
The other point is that the interface that BTAgent runs on isn't exposed to the internet, it is only available from the management network so someone obtaining the keys for BTAgent would also have to compromise the management network - at which point bt has bigger problems!