I think you will find that some of it is related to credit card verification and the rules that credit card companies impose. In the UK, under certain circumstances, the card companies won't approve a transaction without the post code. Yes, that's as well as the two factor authentication.
If I were an hotel operator I would probably like to get your address just in case they have to evacuate the hotel and you don't make it out; they can advise the police who can advise your relatives. There are also some governments who have to be told by the hotel.