I believe that vision in intelligent systems must be properly (intelligently?) integrated with the other system sensory input or it will be next to useless (as referenced by sharps) as the command cascade to action will be a ridiculous trip.
Combined vision with voice recognition, for example, would significantly reduce error in input by linking intuitive gestures with voice commands. You could then point at your TV and say "HBO" and the system would combine the two commands into the proper action. Combo input would nearly eliminate false command input because unless both gesture and statement corresponded there would be no action, and more precise action would be enabled because gestures significatnly reduce ambiguity of intent.
Safety, convenience, time saving. Oh, and play, I suppose (for example, all the iPads being sold are really for playing). I must admit that the toilet example by DrQuine struck a nerve. What's worse than the ill timed auto "royal flush?" Our robotically controlled vacuum use more clearly uses automated vision than automated trash lid (dumb sensor) but the latter is no less convenient. Keep it simple s _ _ _ _ _.
One such augmentative machine vision application was demonstrated at this year's CES -- an automotive heads-up display that highlighted (in red) critical objects in the field of vision, like a pedestrian starting to cross the street up ahead.
I think an application like this can definitely improve safety. Drivers will not abdicate their responsibility to look through the windshield, but machine vision just might alert them more quickly to things they otherwise might not notice right away.
I doubt computer vision can really improve vehicle safety unless it is always augmentative.
It is unfortunately human nature to abdicate responsibility to technology. If a vehicle has a computer vision backup alarm, drivers will soon learn to just reverse blindly until the alarm sounds. When something does go wrong and something is damaged or someone is hurt or killed, the driver's lawyers will be looking for someone to peg the blame on.
First do no harm: prevent false alarms. Everytime I walk through a New York City airport bathroom and hear the "Flushing Cheer" as each toilet in turn flushes, I realize that automation is a double edged sword. There is also no emergency stop switch - so stuck sensors waste staggering volumes of water.
Automobiles safety can be benefited from the new sensors but vision sensors are hard to justify. I do think that consumer applications in which we can use sensory input rather than touch can be huge advantageous.