The Church has been 'doing something about it' for the past 20 years. That's why the overwhelming majority of the cases of abuse that have come to light occurred from 25-40 years ago. When it became clear to the Bishops that the treatment recommended by the psychiatrists for the abusive priests didn't work, many began to work on getting those priests out of the parishes. Some were slower to do so than others, but changes were made to reduce the opportunities for abuse.
Most Dioceses had already put safeguards in place, even before the abuse scandal broke out in Boston.
The reason it has come to light it because many of the victims finally went to secular authorities. It became public knowledge and the Church HAD to do something about it.
Otherwise, why did they cover it up for decades instead of dealing with it then? They can’t have just realized for the first time that it was sin only 20 years ago when they had been getting reports of this sort of stuff longer than that.