I am writing a research paper to which this is relevant. I have seen many references that refer to the sexualization of stockings, but none really analyze why or how this came to be, even though many of the sources I have seen go back pretty early. Hell, I think even The Wife of Bath from Chaucer's The Canterbury Tales sexualize her with the red stockings she wears.
God help your research paper. In Chaucer's time all women wore stockings (as did the men). Tights are a pretty recent invention, and trousers were not an option. The point about the Wife of Bath is that her stockings were red, not that she wore them at all.