It's a fashion thing, well I bloody hope it is, my eleven year old daughter has a key on a chain amongst her her collection of many, fortunately I have never seen fher wear it and I can't point it out. I have been tempted to steal it and put it in the bin, but paranoia etc...
We just have to be realistic, keys can be pretty, pretty things end up on jewelry.
Many years ago I bought my wife a pandora bracelet so that if I was stuck for ideas, I could get a charm for it.
There is an enormous selection of keys, locks, locks with keys for it. I am just dying for an excuse to get one.
Thing is, my wife would wear a key if it was pretty and if chastity hadn't entered our lives and wouldn't have thought anything of it, but wouldn't wear one know because its associated with something kinky?