From what you say, I conclude that you know very well before a shoot, wehteher you will capture video or stills and usually it is one or the other. From my observation of videographers, capturing [professional level] video does not leave enough time and room to allow them to also capture stills at the same time during a shoot.
Doesn't just not leave time. It really is a headphuq. Video does require composition, but you have other tools, other rules, you can make a point via montage, you can make a point via sound, your viewer may only have 2s to interpret your shot.
I will generally think in sequences.
Stills: completely different. Compostion, that single frame is your single chance to make your point. I'll will focus purely on that single frame.
So why not just take the requisite camera along for the task at hand. Motion cam when its video time and stills camera, when its stills time. And for the very few occasions when really both are required, you'll want to have two separate cameras anyway ... "typically" one on a tripod (video) and one your hand (stills).
A number of reasons as I detailed in my post. They suit different applications. Let me turn it around. Next time you go to take some portraits you are only allowed to use a 135/leica/minature format DSLR with an 85mm lens. You like? Why restrict yourself? My ENG's and HDVs work great for some applications. My DSLR works better for some. My gopro works better for some.
I'll use whatever tool gets me the results that will satisfy my client and I. I don't care what shape it is or badge thats on it. I'll only use it if it works and if it's the best tool I have available to me.
As also discussed previously, I'm not in the habit of combining the two, there is a work leisure divide.
I rarely shoot stills hand held in any case... I'll usually have a monopod, or a 'pod' or a superclamp.
So, in essence, I fail to see the overwhelming usage scenario for fully video-enabled stills cameras. To me, the sole reason why DSLRs are being abused to also capture video is the absurdly high preice-level of [large sensored] video cams [with a lens mount that accepts a wide range of lenses that are way less expensive than typical video-lenses].
I disagree in quite strong terms. Blame live view, not video. I still worked in camera retail at the launch of the first digital rebel. It cost as much as the 70D does now. It's a myth that video adds costs to cameras. The 5D3 cost a lot more than the 5D3 because its a lot more camera in all sorts of ways, much like the 5D2 on launch cost more than the 5D, it was a lot more camera, and nobody objected to video then.
Just ignore the video bit. Don't use it.
It's not holding you back. It's not holding canon back. Live with it. I wish I could get an EOS in colours other than black, so I bought a white M. I detailed all the functions I don't use on my DSLR. Would canon do me a version pared down to just what I need.
I shoot stills quite seriously as a hobby. My cameras, all video enabled, match or exceed my ability and requirements.
I shoot video professionally, and in many situations my video enabled DSLRS are my goto choice.
Nothing in this life is without it's caveats.