Why go shopping for cute new outfits right before vacation when you could have a whole experience searching for your perfect vacation outfit while you're already out exploring?
When you pack light, you're giving yourself the room to explore a new destination in a whole new way. Try out the local fashion, shop at family-owned boutiques, try something on that you'd never be able to find close to home.
Plus, what you end up buying on vacation is bound to be much more unique and meaningful than anything you'd buy at a chain store back at home. Because really, there's nothing better than saying, "Oh this? I picked it up in Barcelona."