While I not sure I would agree with the view of your evangelical friend (I've been to Orthodox Churches) I believe you make some very valid points about us Protestants and Mary. I too feel that we often diminsh her role.
I will say there aren't very many scriptures that talks about Mary so creating a sermon on Mary is extremely difficult without getting into speculation. Our pastor did a sermon on Mary and it was based mostly upon conjecture. It most likely is far easier for the Orthodox and Catholics to talk about Mary because they refer to tradition.
There is far more information about the lives of Ruth or Esther (even Rahab) then about Mary. Protestants probably don't refer to her as much simply because we focus on Sola Scriptura and there isn't very much written about her in scripture.
Your points are very valid, and I appeciate your candor.
As I pointed out elsewhere on this thread, Protestants really don't hesitate, in general, to use material that is extra-biblical.
Bible dictionaries, commentaries, etc... in use within Protestantism have lots of explanatory and background material that is based on secular scholarship, archeology, Jewish tradition, the deductive reasoning of other Protestant theologians, etc... Protestant pastors have been using such sources for a very long time to spice up their sermons.
The point I made earlier and that I reiterate is that the one class of extra-biblical background and explanatory writings that are essentially never used within classical Protestantism (at least as I have experienced it) are writings done by Christians themselves from the early centuries. These are rigorously excluded from consideration except in very limited situations.