I had no idea that this was illegal in other states. Living in California all my life, I have just accepted it as a normal occurence. Actually, for the people I have known who had bikes, this was their primary reason for buying it in the first place - to significantly reduce their commute time. I have understood this to be the trade-off in choosing to ride a bike; in exchange for the ability to move faster through traffic, you are putting yourself at greater risk of injury or death.
Of course, just because I have accepted this as normal doesn't necessarily mean I like it. I have found it annoying on more than one occasion. And it doesn't seem very safe, maybe in theory but usually not in practice. Do I think it should be made illegal here? I'm not sure.