It would make sense if you could dynamically create custom modes.It means, if you physically print P Av Tv M C1 onto a mode dial, those are all the modes you can have, and you must have exactly those modes, whether you're shooting video or stills. It's kind of a stupid rationalization, at least for now, because the two are almost the same anyways. In video mode, there's no Bulb (duh), and no Fv mode. They both have auto, program, Av, Tv, M, and C1-C3, I believe. And obviously, it's possible to tell the user to turn the mode dial to something else if they're trying to shoot a video in Bulb >.<
I guess, if there were vastly different exposure modes in the future for stills vs video, it would make more sense O.O
Still, some shortcut to mechanically pick particular modes ("I want C3 right now!") would be nice. Could be combined with the on/off switch... and then we are back to the mode dial.