I think it would be a mistake to attribute all of those price changes to deregulation. Lot's of things have happened since then, including improvements in efficiency and technology, insane competition driving profit margins nearly to zero, removing lots of frills and comforts, increased automation (not in the plane as much as everywhere else in the process and org.) If you look at other regulatory environments you'll see similar price drops. I'm sure it was a factor to some extent though - but lower prices is not a good argument for playing fast and loose with human lives.