Well, I don't know about Morgan being a pyschotic opportunist (Empire of Blue Water is actually historical fiction), but I think I know what you are trying to get at.

Morgan and the men who sailed during that era came from men who started out as hunters in the Caribbean who smoked the meat they shot and sold the hides, plus some ex-soldiers, ex-sailors, and others. They all took to raiding ships at sea and settlements, primarily those belonging to the Spanish. Many of them saw themselves as legitimate privateers of some kind.

Now, in the period after that, especially by the 1690s, things changed. The hunters were no longer a significant influence, in fact most pirates were former sailors now. Raiding settlements no longer played a huge role in these pirates operations (that doesn't mean it never happened again, but nowhere near the level that had previously occurred) and attacking vessels became the main concern. For targets, these pirates quickly became very unrestricted about who they attacked. They eventually became referred to as "hostis humani generis" or "enemies of all mankind" as a result. While the pirates under Morgan had stayed mostly to the Caribbean and coast of Central American and northern coast of South America, in the 1680s, some men set out to raid the Pacific, in the 1690s others set out for the Indian Ocean and Red Sea (and again in the 1720s), and plenty of pirates from the 1690s to 1720s raided both the North American east coast and African coast in addition to the Caribbean areas.

If you read/heard somewhere piracy changed, that's what they are probably referring to.