I have been asked for it for discounts - and more recently I've been asked more often. You should definitely request a new one be sent to you - it takes a while, I understand (I think they only do them in batches or something). You would definitely need it if you want to buy Annual Passes. You also will most likely need it if you want to go to the Top of the World Lounge @ BLT (if you are staying there on points).