Writing common wisdom is like all common wisdom: far more common than wise. It's all just tools, and I think what's good for openings reeeally depends on what the story is.

Like the line up there about the person living with their niece: that one seems like a candidate for a more in medias res opening. Whereas the one about the dragon living next door is neat as it is - the very mundanity of the rest of the sentence makes the "oh and by the way DRAGON" pop.

So I think it all depends.