If you are going to have one brake - its better to have it on the front as a rear brake used on its own will tend to skid when braking hard, whereas a front brake wont. There are two reasons why someone would ride without two brakes.
Sheer ignorance and inability to understand the risk it involves.
Has thought things through but is a fashion victim willing to risk lives to follow the latest trend.
Skidding is dangerous and not desirable at any time. Its bad for the tyre as well. On my fixed I have campag record brakes front and rear and I bet when I use them and my legs I can stop a lot quicker than you.
Its a nice feeling if its not the end of the world if your bike gets stolen. But on the other hand why shouldn't we be able to use a nice bike when we feel like it?
If you are going to have one brake - its better to have it on the front as a rear brake used on its own will tend to skid when braking hard, whereas a front brake wont. There are two reasons why someone would ride without two brakes.