Given that Windows Phone is all about the glance and go nature, having to spend a few moments thinking about switching the deviceon, or turning it and then switching it on, reduces the effectiveness of the software.
The two controls on top are all you need to get the essential jobs done with this device, a button for switching it on and off (and taking stills) and the sliding record switch -- this set-up also means you can physically feel if it's recording, even when you can't see it.