One day they'll upgrade their e-commerce systems so that they don't need to take the store offline for several hours when making changes, and we won't have this excitement leading up to a keynote...
I don't think it is about losing sales, rather than ensuring that customers have all the information before making a purchase. Why buy now when in a few hours time you'll have updated models.
Apple's 14 day return policy is great for this, however, seems a bit wasteful and a little hassle, when all you'd need to do is wait a bit and then buy whatever it is.