IS not needed? It's like the brakes on my car.. Yeah, i drive so fast i don't need them..
Well, what if you don't dragrace but decline a mountain? Do you need them then? Not everybody shoots action. And you shoot everything, like a journalist, having fast aperture and IS is a complete lens that can do pretty much anything...
The same goes for my 85, yes it has the fastest aperture available, but I don't only use it for motion stopping, why would I? So when shooting in dark surroundings i could shoot at 3200 is instead of 51200 with a 4 stop IS, tell me that doesn't matter? I could also shoot much much freely with aperture selection, 1.2 isn't always ideal dof...