You ruin the roadway for responsible users by maligning the good name and reputation of your fellow riders when you do so.

I mean to say, riders overwhelmingly want to be safe and it seems to be both self-selecting and self-reinforcing. Outlaw riders are free to ride alone.

Cars aren't essential by that measure.

That really depends on where you live. In many parts of the US, public transit is non-existent, and there isn't much within walking distance.

I think most people in the world -- even outside car-heavy US -- would disagree with that, even if they are not drivers or car owners themselves.