The video format of the Canon 5D MkII was made as 30 fps not 29.97 fps with that specific intention. Reuters reporters were expected to create video for the web with this device. Web can work with 30fps every bit as well as 29.97 fps.
The form factor of the camera is friendly for still photographers so they could concentrate on shooting stills rather than learn a whole new alien interface as well as method of using a camera. Still photographers simply wouldn't have been able to easily adjust to a shoulder mount camera. On the other hand, holding a camera at arm's length and looking at an LCD screen is not very new to them.
What Canon did not estimate is how well the video fraternity took this camera up. They have sold nearly 50,000 5dMkII models and maybe about half as many 7Ds. And now there's the 1D MkIV. Together, through 2010 Canon could easily move probably a 100,000 pieces.
There is probably no video camera, and definitely no pro HD or higher resolution camera that can ever hope to sell these numbers. Even the Red, arguably the post popular pro digital movie camera so far, has sold not too many over 5000.
One of the benefits of making a still camera that shoots video, rather than a video camera that shoots stills, is that still shooters who use the SLR form factor are generally good photographers. They have a strong sense of composition and pictorial language.
They often also make a living out of taking pictures. Hence, by and large, videos from these vDSLRs seem to be pretty decent looking compared to the shaky, zoomy, swimmy videos most amateurs dish out of handycam type video cameras.
Vimeo, Flickr, smugmug, Exposure Room are full of some really great video from vDSLRs. Perya, Dublin's People, Nocturne, are just some examples.
Granted, they may be unsuitable for broadcast, but there is a huge, not-recession-ridden market of wedding video, corporate video, and internet video that can benefit from vDSLRs.