I leave the lights on all the time on my car. They go off when I kill
the ignition and open the door; they go back on when I start the car.
I feel it increases my conspicuity, and it hurts nothing. I'm happy.
I do about 30,000 miles a year in that car.

My wife's car, which I drive rarely, does not handle the lights like
that, so I've been known to drive in the rain without lights. I
usually remember, but not every single time. Steve will say that my
brain is separated from reality at the time, and that might be true,
but habit is a powerful force.

Yet, some people run around with this brain-reality separation a large
percentage of the time. I also agree with HLS -- many people just
don't give a damn. Would switching the lights on with the wipers make
people stupid? I don't think they would any more than automatic
tranmissions, anti-lock brakes, safety glass, air bags, seat belts, or
any of the other built-in safety or convenience devices already in use.
What they would do is ensure that the lights go on with the wipers
whether the A-hole behind the wheel wants them on or not.