I think piracy and privateering should be better represented in EUIV. In real history, this scourge was an important feature throughout the whole period EUIV portrays and which actually brought empires down to their knees. The Spanish empire suffered tremendously because of pirates; the English piracy and privateering was one of the reasons the Spanish sent the Armada of 1588.
In EUIII you see a few pirate ships appearing here and there every now and then but they're never any real threat. Here's a few ideas. In EUIV, state-sponsored pirates could prey on the trade routes. You could issue letters of marque aimed at specific nations; taking diplomacy hits while weakening their trade routes and perhaps getting a cut of the plunder. The states being targeted by pirates would have to tie up naval and military resources to deal with the threat. Pirates should flock to weaker nations issuing letters of marque against strong economies (like England vs Spain). Diplomacy hits for the nations issuing the letter of marque should be severe. The pirates themselves could be AI-run as far as I'm concerned.
In EUIII you see a few pirate ships appearing here and there every now and then but they're never any real threat. Here's a few ideas. In EUIV, state-sponsored pirates could prey on the trade routes. You could issue letters of marque aimed at specific nations; taking diplomacy hits while weakening their trade routes and perhaps getting a cut of the plunder. The states being targeted by pirates would have to tie up naval and military resources to deal with the threat. Pirates should flock to weaker nations issuing letters of marque against strong economies (like England vs Spain). Diplomacy hits for the nations issuing the letter of marque should be severe. The pirates themselves could be AI-run as far as I'm concerned.