A flashing strobe light would affect people prone to seizures. However, many motorcycles have flashing headlights specifically for this reason, so yes, a flashing daytime running light would be even better. They are only illegal because cars with flashing headlights look too much like unmarked police cars.
Regular headlights are every bit as good as DRLs. Strobes would cause visual spots in many people, interfering with their ability to see you, and as Whitey pointed out they can cause seizures in some people.