I'm going to chime back in here because I think both the yays and nays have valid points, but, ultimately, I think no one ought to feel that she is doing something wrong whichever choice is made.
Like some of the other forum members, I'm old enough to remember when going without hosiery in public, except in the most casual of circumstances, was totally frowned upon. Then the next generation of young women told their mothers it made no sense to wear sleeveless sundresses and strappy sandals with hose in the warm summer months--and they were right! Hose was hot, uncomfortable, and totally unnecessary. The catch was your toes had to be manicured and polished, but that seemed a reasonable trade-off especially since mani/pedi places were popping up all over.
But there was a catch for older women. As you age, it's harder to keep the skin on your legs smooth and supple, and wearing shoes sans hose often led to painful blisters and raw spots when walking. Some of us began to long for our hose on certain occasions. Wearing tights was OK in colder weather but sometimes we just wanted the look of pretty, polished legs under a party dress. And, for some of us, fishnets just couldn't shake their less savoury connotations.
Then Ms. Middleton showed her shimmery legs in public and those of us who always had kept our love of hose as a part of a dressy look felt a bit better about giving our opinions about the merits of hose for certain occasions for some of us. If a youthful fashion blogger can be "edgy" when she wears ankle socks with pumps, or black tights with white sandals, why did I need to feel bad about wearing a pair of sheer hose to make my legs look like they did a few decades ago?
Here's the deal--I won't wrinkle my nose at the ripped and torn jeans you are wearing to the party, if you don't turn your nose up at the nude, sheer hose I'm sporting with my pretty dress and shoes. Let's both of just enjoy wearing what pleases us and makes us happy. End of my rant.