@Oberoi0 It's definitely an interesting idea. My thinking is that Airbnb already has this information securely stored. If there is any problem, the police can always contact Airbnb to obtain any identification documents.
There is no way I would ever want to be in a position of being accused of identity theft by a guest.
I know that some hosts are willing to take that chance, but there needs to be a way of opting-out (or not opting-in) to such a program as it would not be fair to put all hosts at risk because of the few that prefer to have posession of this type of information. It also needs to be clear to hosts and guests who is responsible for any data breech. Is Airbnb responbile for a host's security lapse?
It's a very risky idea, but with the proper safeguards in place, it might be workable.