As a man I'm all for it. But I think the women I know would object to walking at night on pitch-black streets.
Cars have headlights. It could be that pedestrians can carry lights too. We could reduce infrastructure costs, electricity costs, allow pedestrians to be more conspicuous, and reduce the other negative impacts of constant lighting. You could even fund these personal lights for lower income people with the infrastructure savings.
Receiving bounced waves gives you information, while emitting it gives out information, and may make you a target. A streetlight is a neutral-emitter that doesn't usually need to worry about being attacked, unlike a bobbing flashlight held by someone walking in the dark woods.
A difference with car-headlights is that the car itself is a protective shell, and it's hard for other cars to hide in bushes.
So yeah, you can give out some information by holding a light, mostly about position. You give out much more information being in the light from street lights, such as sex, age, weakness/disability, etc that are more useful to criminals.
The are plenty of areas without street lights or with minimal street lights today. The primary issue as it pertains to crime is not a lack of street lights, but other factors such as socioeconomic factors and defensive knowledge.
Aye, on my midnight walks when I can't sleep (middle of nowhere - no streets, never mind street lights, it's all trails and fields. Amazing for stargazing!) I use my watch in flashlight mode to see where I'm going wherever it's particularly pitch black. I've also got a backup make-everything-daytime strength torch on me too if I need to properly see something or take out someone's night vision long enough to leg it
Never needed to use the latter so far. I don't imagine anyone trying to prey on me would even see me (or me them) until they're right up close if I turned the watch light off.
Fun tidbit for any new midnight walkers: Your night vision is separate in each eye. If you do need to use a light source in the dark, close an eye before you turn it on. That way when you turn it off you can open the eye and still mostly see where you're going while the other eye catches back up :)
I learned it doing backstage work at a theatre, I also heard it's the actual use case for pirate eye patches -- swap eye when going above and below deck. Good times.
As a kid, I also learned your eyes will individually adapt to not only brightness, but color.
The front door to the house was open and I put my face with my nose along the edge of it. One eye faced indoors, one eye faced outdoors. After a short amount of time I pulled my face away and it was quite clear that color in each eye had adapted to what it was seeing.
fun but weird.