A slave collar was. . . well, just think about it. Some how a lot of sexy females ended up wearing one; but not for long enough. Leia in Return of the Jedi, Asoka in the Clone Wars cartoon, Alema Rar, Jaina, on that cloaked golan in the Vong War, the list goes on. It's possible some of them liked wearing them too. Pretty much all fanboys like seeing them wear them as well.