1. You don't want to create dust while doing brake work because there might be a*****estos in/on parts.
2. The rotor surfaces have to be not only flat but also parallel. Although you did a great job to make it shining but they may not be flat, let alone parallel.
3. What you have done might be equavalent to remove rust, which may not be necessary since the rusted part is normally not in contact with pads. I changed brakes for my old Mazda before, did not bother to resurface rotors and braking was quite and smooth.
4. Didn't see you mention to condition the brakes by slow braking for sometime; instead you tried 70 mile/hour braking tests. This might be equavalent to sand the rotors with brake pads.
