HK There is a difference between a flashing light and a constant one, just ask an epileptic. Flashing lights don't allow your eye to become used to it the same way a solid light does so appears more intensely blinding & annoying.
Pointing down doesn't mean facing it at the ground, it means angling it in such a way that the full focussed beam is not pointing directly into the drivers eyeline, it can be an almost imperceptible change to its angled position on the bike to make quite it quite significantly more comfortable to oncoming motorists. When you look at these things, you need to be sat at driver level and a w**ker sign distance away so you are seeing it in the same context as those who are (supposedly) making gestures at you are.
It may help to get someone with a car to drive towards you out on the road whilst you have your light on flashing mode and tweak the angle with their input, then repeat this driving towards one another until they tell you that you are visible without being annoying.