Lights certainly should be properly aimed. Of course, that presupposes people have proper cycling lights in the first place. (Sadly, far too many simply mount flashlights, or 'bike' lights with a flashlight's beam pattern.) That said ...
As for flashing, I regularly ride on a few roads with sufficient blending-in that occurs with cyclists such that flashing lighting is far more noticeable (and at much greater distances) than lights that just sit there. Can't be said of all roads or traffic patterns, but I find the difference to be striking frequently enough that I always use a flashing one in my arsenal in an attempt to be seen.