Hate to be the guy who points out menial grammar mistakes, but you said "and" when you should have said "or". What you said implied that one cannot ride fast even on well lit city streets without hundreds of dollars worth of high quality lighting. That is obviously false.
"A $20 front light is useless unless you're riding in well lit city streets or going slow."
With a $20 front flasher you can ride as fast as you want in city streets, and be just as safe as if you had a $220 headlamp. You've demonstrated that yourself with the VistaLite Xenon... <$20, and it attracts attention, which is 100% of the job of a bicycle light on city streets.
Are you volunteering to be my grammar corrector then?
When I was in third grade, my teacher asked me a question of which I can no longer remember, but I replied using the word "ain't", she was mortified and asked where my grammar was, I told her my grammar was in the kitchen baking cookies!
Actually when I said "and" I meant and! If your riding on well lit city streets AND going slow...but I also meant or, so I should have said if your riding in well lit city streets and/or going slow.
flashing front light attracts attention regardless if on a city street or in the country, the car will see that first only because bicycle head lights are small and they can misjudge how far away you are. But you can't see the road with a just a flashing front light, you need both, or should have both, the need to have is up to the rider. Not all city streets are well lit, you also travel from one well lit area to a non well lit area and your eyes are not accustom to the dark areas very well, so with a light you can see with those dark areas are now lit.
Look man it's up to you if you want to see the road better, most people in my city of !80,000 people don't use any lights flashing or not at night, and a lot of those people don't even have reflectors! And they can see to ride...sort of, but we can't see them well at all.