The reason to license dogs use to be two fold- 1. to make sure that people were having the dog vaccinated for Rabies and 2. If the dog got lost, it was a means of reuniting dogs and owners.
Private industry has taken care of #2- microchips and services such as the AKC Compaion Animal Recovery (Care) program, Home-Again, and other recovery services have mostly taken the place of the need for a license. Animal shelters are required to have microchip scanners and we would all like to think that they use them to help find homes for dogs picked up on the streets.
As for #1-well, all warm blooded animals can harbor Rabies- so why don't we license cats? More cats are unattended and roaming the streets than any other domestic animal. A bite from a cat with Rabies is equally as serious as a dog bite.
I guess that the only remaining reason to license dogs is for a "dog tax". It also serves as one more way you can "stick it" to your neighbor that you are having a dispute with- just call the "dog warden". Dog license provide good money to counties, townships, States, and so it is un-likely that anyone will do away with them- but this year, as you are renewing your dogs' license, ask yourself, is this money being used to HELP me and my dog. I think you will have to answer no- maybe a movement will start that says- "Hey Township- it is none of your business how many dogs I have! and I am not going to pay you any amount of money so that you can come knock on my door to see my rabies certificate."