Just because something isn't explicitly set out as being mandatory in the rules/laws doesn't mean that it's not a good thing to do. As a recent Horizon documentary showed, the vast majority of people in the UK refused to wear seatbelts for many years after they became mandatory in all cars sold there, due to a perception that they would actually restrict you/impede your escape in the case of an accident.

And quite frankly, I find the suggestion that airlines should simply observe the minimum mandatory safety standards, and not consider doing an iota more, a rather strange one. I'm sure that any airline worth its salt would require all such reading matter to be stowed as standard procedure when preparing for an emergency landing, whether or not they do this as part of their normal procedures.