I have lived in areas that have had cycle registration in the past. Supposedly it was so your bike would be listed for easy return if stolen. I have had several stolen over the years that were registered and have yet to get one back that way. I asked about the old registration records recently and no one has a clue what happened to the data base.
FWIW I would not support registering or licensing bikes or the riders. I can see where it may be necessary in say a college environment to control the number of bikes and where they are parked. I know at University of Iowa they will ticket your bike if it is locked up somewhere it isn't supposed to be.
Aaron