hey were outlaws, murderers, thieves and hated back in America's discovery ages

Not that true at all. For the 1680s to about 1710 or so, pirates weren't really that hated in the North American colonies when they went and raided ships of other countries mostly. A number of pirates found welcome in those ports, along with their hard money and often rare valuable commodities they brought back with them. That changed in the 1710s as authority to try pirates changed, as the target of pirates changed, and as politics shifted and pirates became a weapon in political struggles (as in, "Mr. X allowed pirates into his port, he should be removed - also, put me in his place, or at least someone of my political party.").

Another point, in most modern media we don't actually see pirates doing much pirating. Take pirate of the Caribbean, the only characters who actually raid, pillage, and steal ships are the pirates we are supposed to dislike, at least in the first movie.

Because for many they represented a life of freedom. There was always something exciting about living a life outside of the law. These were larger than life figures that terrorized the Caribbean and the coastlines of the world. There has always been a large interest in them. Pirate executions were public events, and remember, Treasure Island was written in 1883. While it was long after the golden age of piracy, it still shows that the public has had a long fascination with them.