neuroanatomist said:
IS is just another thing which adds complexity to the lens
The complexity of stabilizing video footage in software is much higher than the complexity of turning on IS on the lens with the switch of a button. Most people have neither the time, or desire, to spend hours doing post process stabilization in expensive software. Not to mention trying to stabilize footage in software crops part of your image.
Canon realizes that video is popular enough, that all APS-C zooms now come with IS. 10-18, 18-55, 17-85, 18-135, 18-200, 55-250, they all have IS. Canon no longer produces APS-C zooms without IS.
Even smartphones now comes with IS. Having wobbly video footage now looks amateurish. Even from a wide lens, it wobbles enough that it looks like it was shot on an old point and shoot.
If you believe IS adds complexity to the lens, you must buy all lenses without AF, because that adds quite a bit more complexity than IS does. At this point, IS is a must for most people.