If your thinking of a light switch for starting purpose the lights are disconnected anyway while cranking through a lighting relay. If you just want to kill the lights anyway..... energize that same relay with a aftermarket handlebar switch.

blackrider- curious. Why would you worry about it?

Joe - interesting vantage point! Right under my nose.

Steve - I dunno, worried about battary fatigue during stop-and-go, commuting and congestion? You wouldn't believe how many traffic lights there are in central Tokyo.

I guess I just like having the choice as well... all safety issues notwithstanding.