Hello,
I know this is quite an old topic and the passage of time suggests that TfL are not too interested in implementing this feature, but I just wanted to add my name to the list of people hoping for live bus and tube departure times to be included in the Unified API. It would really help us to create apps that are useful for people living near terminus stations. I know other services are able to provide this information (for example traveline sw, which is possibly what Google and other apps rely on) so I would hope it is technically feasible to add it to the Unified API.
If I should direct this feedback elsewhere please let me know.
Thanks