Deborah, it is fascinating indeed. I wonder also if some of our perceptions are not based on geographical/ cultural differences and even what the stores in our different areas sell.
I wonder if the association to opaque tights is to little girls' leotards? (What we called them in Canada when I was a kid -- not a true ballet leotard but the tights part). I think I can see that.
The thing is, I do actually wear opaque tights a lot in winter. And have been wearing them for years (though obviously with different dresses than the new one.) Basically, I wear them whenever I wear a non-formal dress. Because I have to, or else I will freeze.
This makes me wonder, too, if someone living in my climate would tend to read them differently due to constant exposure. As Carla said, in Toronto (where I grew up) the city is a veritable sea of black and grey opaque legs as soon as the temperatures dip. Montreal is pretty much the same.
And these legs are all clad in tights -- not leggings (except worn as pants substitutes with long sweaters.)
I'm not saying this is a good fashion look, necessarily. It's seldom worn with intention. It's worn because it's what is available and what is practical, and nobody really thinks twice about it. I hope I won't wear it that way...but at the same time, I know that in my environment, it "blends." If that makes sense.
Meanwhile, I have a feeling that people in Oz may be more practiced at wearing leggings. This is based on crazed conjecture and no real data!