To my understanding SolidWorks always includes a Point as a sketch entity, if Midpoint line is being used.
So, what is kinda workaroundish thing, but doesnt have the annoying Point entities is to draw arbitrary line and add a relation from its midpoint to the second entity you are using.
Yet more - there is even a relation named Midpoint which attaches line's midpoint to a vertex or a point without pre-existing Point (as a sketch entity).
[EDIT] So, yeah... I dont use midpoint line anymore
