good point. if i want to use a point for this i make a point in a 2d or 2d sketch and use it as you describe using the parallel to a plane at a point option.
I'm not sure what you mean by "can't mate to them." I just used a reference point for mating. Specifically, I've got two tubes with beveled ends which need to be mated. One of the mates I use is to create a reference point (in one of the part models) in the center of the beveled face. In the assy, I mate the reference point to the top plane.