Since Cetalis addressed much of this I'll try to keep this reply short.
A previous poster described in detail how the design process worked, and why it is more difficult to design a product to do two different things.
I saw little detail, and no references. That long "explanation" seemed like handwaving to me -- all suggestion, no substance. I saw little value in it.
They had to use a bigger CPU, which has more gates and burns more power when it is doing those other things.
Performance per-watt continues to go up for mobile devices. As an example, consider netbooks, which have the performance of a Pentium 3, and use a trickle of power. And yes, one of the strategies is to idle the processor, or to idle parts of it that aren't being used. If that were not true, your camera would quickly run out of power just staying "awake."
I don't want a different, heavier, higher-capacity battery...If there is new battery technology, I want smaller and lighter, not the same size with more capacity.
This is legitimate, though some people do want higher capacity at same size/weight.
Wasn't sensor heating and noise already mentioned?
Mentioned? yes. Addressed well? no. Sensors only heat when active. If you're shooting stills then this is no problem for you. So what's the problem?
Note that even the Leica M9...Strawman.
You did not specify how this is a strawman so I'll have to guess. If you mean it's irrelevant because it's not a Canon then I disagree. The premise of the anti-video crowd is that adding video features inherently undermines still photography, and that a camera that was designed, ground-up, as a stills-only camera would produce better-quality stills and a better still-shooter experience. The Leica is a counter-example to the assertion that stills-only produces better IQ, even though it is a substantially larger sensor and was selected/designed for stills-only. If there was something else you considered to be a strawman, please specify.