I just built a store in Commerce using Drupal 7 and I am taking payments by the Commerce PayPal WPS submodule. However, when I tested checkout, I found it was possible to buy a product without supplying a shipping address.
In the PayPal Express Checkout documentation, it shows there is an option for forcing users to provide an address. However, the WPS documentation is less comprehensive and does not include any information about whether it is possible to force a shipping address to be displayed or not.