several states and the Motorcycle Safety Foundation recommend in their endorsement study guides to run hi beams during the day, at a minimum (Hurt, 1981)
Hurt, H.H. Jr., Ouellet, J.V. & Thom D.R. (1981b). Motorcycle Accident Cause Factors and Identification of Countermeasures. (DOT HS 805 862). Washington, DC: National Highway Traffic Safety Administration
National Agenda for Motorcycle Safety
If I'm on a country highway at night, I run main beam only. But nighttime in an urban setting with streetlights, I run hi beams as well. The overall lighting environment is higher, so it's less blinding to drivers, and it helps to make you brighter than everyone else, which is THE POINT, because cagers need help in seeing objects that move faster and are smaller than other cars.
But as stated previously, on a lonely interstate or empty two-lane road at night, if you pass me, I'm either on my main only, or I've just switched my hi beam off (because I saw you coming and don't want to blind you). But in a multiple car setting at night, such as a major highway or boulevard going through a downtown area of a large city, you want both beams on; you're not blinding people in that situation.