Well, one problem with voice dialing is you need to press a button to activate. If I could address my phone while it's sitting in my pocket or on my desk and initiate the call with a voice command while reaching for it, that might actually be sort of useful.
The Xbox voice recognition, for all its hype... totally sucks. It messes up channel names. Even though it has context to go on. It literally is incapable of switching to Fox Sports 2 by voice command. It always goes to Fox Sports 1. It messes up lots of other channel names too. But at least with other stuff I've found that if I go into hyper-enunciate mode I can usually get it to work.
But, compared to my almost 4 year old Android phone.... it's nowhere near as good. If I click the voice thing on the touch keyboard... with no context, it figures out "Xbox watch fox sports two" with no problem. I don't even have to go into hyper-enunciation mode, though I do make some effort to sound clear. Granted, I'm pretty sure the google voice recognition is done server-side... but it just plain works better than the supposed wunderdevice Kinect 2.0.