I'd like to bring this thread back to life because I'm looking for the exact same thing as OP.
We use the BCS Quote module, which requires the user to be registered to submit a quote request. The problem is that if a customer registers simply to use use the quote module, they're never *required* to add an address to their address book. It can cause the problem of us not knowing where they need their stuff shipped for proper shipping quotes. If the registration page included the address fields marked as required, then the problem would be eliminated as EVERYONE who registered would have an address filled out. There is no reason for a customer to register on our site and not have an address in their profile, as for them to make use of our site they have to buy something that is shipped to them
