What a loaded subject!
I run all my runs during the week in the dark, after work and sometimes after dinner, and this time of year, that means it's always dark. I run up and down the streets of my residential neighborhood, which are mostly lit by streetlights, but in some cases are not.
I never use a headlamp except for a rather dim red light so i can be seen by the few cars i might come across. And i wear lots of reflective running apparel (i.e.: running vest). But the reason i don't wear a headlamp is exactly in line with the fears expressed by many in this discussion. I simply don't want to limit myself by any fear of running in the dark, and if I use a headlamp, i'm afraid it will become a crutch, so to speak. So, just about my entire route is hills and i commonly run the downhill portions at a fair clip, which for me, is about 7 to 8 min./mile pace, and in the dark, that takes a little bit of faith.
For all that, i can tell you it is tremendously exhilarating. The neighborhood is delightful, hardly any traffic, there's people out walking their dogs (including women alone), and i get to run in the streets. Please note that during the day, i only run on the sidewalks since I would be unaware of a car coming up behind me, but at night, the light from their headlights warns me well in advance.
The only falls i've had have been on the sidewalk and that was usually because i was looking at something else and missed seeing a big rut or something.
As for the risk of getting attacked, that basically is not very likely in neighborhood which is upscale and comparatively safe. I asked my wife if that would be a view shared by a woman and she says, yes, especially if your are running.