I disagree, I think motion blur is an important addition if the graphics hardware can afford it. Games tend to run with no motion blur at all, effectively being a series of very fast slides, and luckily your brain is clever enough to see motion from this unnatural sequence of images. Add motion blur (which happens with real film), and a still image also contains information about motion, and the brain can extract more information about what is happening on-screen. Try playing a game at 20fps with motion blur off then on to make the difference obvious. When it's on, the low framerate is much more tolerable, because instead of seeing a still image for 50ms, you're looking at an image with motion information.
In fact, motion blur is a form of antialiasing, but through time rather than through space. Therefore anything to make it more usable is a good idea.