why do they make fancy underwear?

We have been lucky enough to have been given lots of hand-me-downs for our kids. One bin of clothes contained a pair of La Senza cotton underwear, white with pink polka-dots, with lace bands around the waist and legs. Recently when Taylor was wearing a dress she kept pulling on her underwear. I asked her what was wrong and she said the underwear was uncomfortable. What she actually said was, "Why do they make fancy underwear anyway? It's not like anyone's going to see it!" I decided it was not the time to explain to her the circumstances under which someone might see her underwear, or why she might even want someone to - especially if it was fancy!