Just because coin throwing and other non-acceptable crowd actions have been taking place for many years, is no reason for not taking any action. Why do football supporters act in this manner, after all it is only a game.  People say you can become so involved in the game and your emotions take over. But surely this can be said of supporters in many other games, but they do not resort to actions of this nature.
Over the years there have been other spectacles that have had similar supporters reactions, what about the Gladiatorial Arenas of the Ancient Romans.  It was not right then and it is not right now.
What actions can be taken, well you can have zero tolerance, CCTV, plants in the crowd and the crowds to police themselves, or a mix of all of them plus any others. 
The point is no matter what it takes, action to stop this and other similar behaviour needs to be taken and be taken now.