You know, I could see that ruler as being useful for freezer paper applique too. It could be used to draw the leaf shapes on freezer paper (instead of cutting fabric), allowing lots of freezer paper leaves to be drawn at one time. Or, it could be used to cut the leaf shapes directly out of freezer paper.
I agree that quite a bit of pressure would be needed to cut more than one layer of fabric using the template. I have found cutting around curved templates with the small rotary cutter to be rather awkward for me.
Since the small template makes quite a range of leaf sizes, I am thinking it would be enough to get just that one template. I didn't look at the other sizes, but they would almost certainly be overkill for me.