Pizzaboy had it right when he said the days of Frank Costello are long gone. In his day, Mafia rackets tended to be fairly well hidden from the public, or considered "victimless" crimes--gambling, prostitution, labor racketeering, etc. Of course there were victims, but generally the victims were people society didn't care much about, such as blacks and Hispanics addicted by Mob-imported drugs, degenerate gamblers who were loan shark victims, crooked labor leaders "who got what was coming to them." Omerta was easier to enforce because Mob guys had to be caught in the act to be prosecuted--the bosses were well insulated, and the street guys were seldom convicted of crimes that carried big sentences.

Three big factors kicked in starting in the Sixties:

--Children of nice, white, middle class parents (including children of law enforcement, politicians, judges, etc.) began getting addicted to drugs, which woke up the cops and resulted in big sentences.
--RICO established a legal framework for prosecuting and convicting Mob bosses by linking them to criminal "conspiracies." Even victims of Mobs (such as a degenerate gambler forced to bust out his business to satisfy a debt) could be prosecuted for being part of a "racketeer influenced criminal organization." Double-digit sentences from RICO and drug convictions made a shambles of omerta.
--Italian Americans and other ethnics with ambition started going to college rather than joining Mobs. Result: the Mobs are headed by the John and Junior Gotti's of the underworld, instead of smart guys like Charlie Luciano, Frank Costello, Meyer Lansky, etc.

As for better law enforcement:

At the conclusion of his definitive "The Five Families," Selwyn Raab noted that after Rudy Giuliani showed how RICO could be used to bust the highest levels of the Mafia, federal prosecuters all over America were in a rush to do likewise in their cities--nothing succeeds like success, and there was much glory for law enforcement. But since 9/11, he added, a lot of law enforcement resources have been diverted from organized crime to terrorism.