And when shooting from a car, boat, or airplane, a tripod would accomplish what? Or what about shooting in venues where tripods are not allowed? Or you are shooting from a tripod, and there is a strong wind that is still causing camera shake? I've encountered all of these situations when shooting.
[a href=\"index.php?act=findpost&pid=165888\"][{POST_SNAPBACK}][/a]
Then a mono pod, resting the lens on somebodies shoulder, whatever. Its the 'can do' attitude people had before IS became a crutch.
A point is well made by Farmer and it pretty well answers your conjecture re in-body IS being inferior to in-lens IS for the examples you give. There is a ratio where it no longer matters what your IS is capable of, or how big the mirror box or image circle is. The logic of this ratio says that the more stops of IS compensation there are, the less likely it is that the camera will be even pointing in the right direction. The camera will provide a perfectly sharp picture, but not of what you pointed it at. It changes from lens to lens, but the laws of physic's can't change, if you move or shake a 1000mm lens enough, on your swaying boat, it won't be centred or even focused on the subject, and light rays can't bend and the camera can't read your mind, yet.
So whichever way you look at it, with the current design of the cameras the lens based IS is at best limited in the sense there isn't much further to go with it anyway, other than finessing it. Which brings me back to my first point. Canon sensors are out out resolving the lenses so there is limited growth in the full frame system. APS-C sensors are getting better and it won't be long before they are as good in every way as whatever the equivalent full frame sensor will be, perhaps better. Experience from all other walks of life suggests technology gets smaller AND better. So, a new range of lens (based around APS-C), with a shorter length and size, al la Olympus, would eventually yield a more significant gain in resolution and overall performance than the outdated legacy designs. And given this philosophy I am arguing for the idea of in body IS. It becomes workable for as many stops as is feasible before the 'ratio' takes over.
I can only think of one good reason why photographers would want to carry around the large monstrosities they do now, given an equal choice. But take that choice away and make a better range of leses and they'll just go and buy a bigger car instead.