As a school librarian, I have quite a collection of costumes: book characters (like the Snow Queen), pirates, pioneers, and the like.  I can see a great advantage in virtual costumes. As I prepare for immersive learning environments (The Land of Lincoln) or re-enactments (The Alamo), it seems that some of the advantages of virtual costumes include savings $,  cleanliness (no problem spilling a drink), the ease of storage (you should see my guest room closet!), and the creativity (you can make them or find creators who specialize in them).
So many of the things in real life can be recreated in virtual worlds.  When I look at the advantages, I also think about how very special the real world will become when we utilize the virtual world for our basic projects.  Things worth making for real will be appreciated instead of simply added to a heap of mounting trash and clutter.