If I’m going to be simple about this, basically, tiers of Pirate Captains (Rookie, Average, and Strong) have dialogue dedicated to them. Rookie Captains may say that you’ll be one of the first to fall under their might when spotting you, and they may say they regret entering this life (“I should’ve remained a blacksmith,” for example) when defeated. Average Captains may have the average dialogue for pirate captains when spotting you or being defeated. Strong Captains may call you another footnote when spotting you, and may mourn for their treasures/ship/crew or commend you for your strength when defeated.
So, why just Pirates? Why not the GN and AS? Pirates have no discipline or order, so they don’t need to be bound by shared dialogue for all Captains like those from the GN and AS.
I just think it’ll be neat to add a bit of variety to Pirate Captains’ dialogue for worldbuilding (?) sake.