How do you -- if you do at all -- square protagonists who would be the villains in a different genre? What do you do with the crimes they commit? Are all your criminal heroes "thieves with hearts of gold" like Han Solo, or do you indulge in the grittier side of these stories? And if your "heroes" are rough, how do you make the villains stand out?
For me, oftentimes, the thieving is a backstory. We don't spend much time thinking about exactly what Han Solo smuggled*, because it all took place before he did the things we really care about him doing. Likewise, character X in my game Y will often have developed their skills used in acts of derring-do through an unseemly backstory, but that's usually (mostly) in their past -- be that because they've turned a new leaf, or simply because now they are doing bigger and more important things.
*And even Conan -- who is often a hero mostly in the pre-modern sense -- still does most of his piracy, banditry, and marauding safely off-page.
When we do play thieves who actually thieve, or pirates who actually pirate, it is with a conveniently deserving victim. The big bad enemy nation, the robber baron merchant house, 'the Mob,' or the like. The modern Robin Hood depiction is popular because we can see a crook as a plucky underdog if the person they are committing their crimes against is sufficiently odious (or, to jump genres, in
John Wick we can get behind an
assassin if the people they are up against kill a beagle).
Or it is a crapsack world like Doskvol where it's implied that everyone still alive is willing to be dishonest to survive and both any realistic character in that setting and anyone they take from are all somewhat morally compromised (and even there, you'll probably run into a situation where you're stealing food money from an orphanage, and realizing it's '
Fagin's School for Boys' isn't going to make that sit well).
It should be noted that there were historically also plenty of pirates who were decent people. Just because a person lives a life of crime, does not make them a villain.
We have to be careful about what we are calling "crime". Stealing property and money from the rich is one thing. I expect most of us don't actually care about property crime so long as you aren't leaving people starving in the process.
This is a whole IRL tangled knot. Exactly what you can do and still be 'decent people' has a lot of nuance; and I absolutely care about property crime and not just that that leaves people directly starving, but that which destabilizes basic avenues of commerce upon which any number of innocent people rely on to live their lives. We could have an entire forum, or even a life's work, dedicated to the nuances of 'just crime,' just as one can to 'just war.' However, that's often the kind of hard reality I'm deliberately trying to escape when I roleplay.
Sanction to turn your atrocities against a rival nation doesn't make them less atrocious.
Violently taking another ship at sea, such that human bodies are torn asunder by cannonballs, wooden shrapnel, and cutlass wounds is another kettle of fish. Kind of hard to be considered a "decent person" when your job entails leaving a wake of fire, blood, murder and death.
Piracy is basically just a form of theft. It can involve violence, but it doesn't have to, and often didn't (many preferred not to be mortally wounded, what a surprise). After all, many pirates preferred their victims to surrender without a fight. Atrocities are not a requirement for piracy at all, though a few notorious historical pirates loved commiting them all the same. There were some really cruel pirates.
But intimidation only works if the threat is credible. That generally means actually using violence on occasion to establish that you mean it. Blackbeard took the ship he later renamed the Queen Anne's Revenge by force only after firing a couple of broadsides and killing several men upon it.
"I only sometimes murder people," isn't a ringing moral endorsement.
At the end of the day, IRL piracy is theft through the threat of violence. There isn't a lot of ways to make that somehow 'decent.' However, there were significant times and places in history where non-bloodthirsty pirates would intercept ships with crews with no interest in dying for someone else's goods and said
'you know the drill, hand it over' and everyone went on their way unscathed. That's a nice window for relatively non-awful pirating to happen in a game. Likewise there is the wartime sanctioned piracy as part of war. That's certainly not worse than, y'know, just warring against/killing the other side. And there are plenty of games where we do that (or similar).
Regardless, I don't think the justifications matter all that much. We (my groups, to be clear) don't do a lot of actual piracy in our games because no one actually wants to do much of it. People
want to be
the pirates who don't do anything -- it is an aesthetic, a motif, a set of genre elements that work well to facilitate an group of adventurers with violence and adventuring skills, mobility, and the relative freedom to go seek the lost treasure of X or defeat the curse monster of island Y or whatnot.