A load of cultural hype and cutting through a bundle of straw isn't that amazing when compared to the massive trauma created by a heavy blade vs flesh (and bone for that matter), or a .70 lead ball fired at a target a few paces away, which is known for doing very horrible things to flesh.
Ceremonial hullabaloo and duelling "weapons" for 1-on-1 combat got nothing on purpose-built practical solutions. Especially pistols. Katanas are known for being slashing weapons that have trouble cutting through bamboo vests and effectively parry other katanas. Ignoring all the other blades pirates had on hand, cutlasses were best suited to the close quarters combat of ships and could even chop through thick wood.
And this ignores actual combat situations. Ninjas would be committing suicide by hopping onto a pirate ship as anime-inspired jumping and dancing will not save them. Trying to attack a mob of pirates in a field would also be stupid, as the majority of pirates would be ready to shoot on sight (dodging gunfire happens only in the Matrix) and still have number superiority after they've all fired at least once.