As for implementation, it's rather difficult to say. I've never really looked into it, but it might be possible within the regulations or the act.
I understand that these kinds of events might lead to more expensive tickets. If there was more promotion of tickets without a reservation, consumers would know ahead of time that they might not be able to get on the plane, thus lowering the possibility of a nasty surprise. However, that's not what happens at the moment. People buy a ticket, and at the last minute, find themselves high and dry, which makes no sense at all.