It's very bizarre to me because you'd think golden age piracy would be perfect for games, particularly RPGs. It's an untapped well of potential that nobody has zeroed in on, a lot like how it took Rockstar to finally break the seal on an open world Wild West simulator. Hopefully in another five or ten years we'll get a Suckerpunch or some other studio to finally get the goodwill to capitalize on the potential, and they can pump out the game everybody's been pining for since Treasure Island hit theaters.
I think what scares devs off is when you make a game about something like the old west or the golden age of piracy you run the risk of coming off as very generic given how well worn these tropes are in the culture, people might take one look at a game and assume it's shovelware if it's about somehting as simple as "cowboys" and "pirates" even if it's not.
What Rockstar did with RDR was they came up with a clever hook and story that made it stand out, the idea of taking place at the very tail end of the wild west era, that was what was needed for the inspiration to flow and for the game to succeed by making it clear it wasn't generic, while still being able to deliver the tropes you'd want to see (but in a fresh way)
It's also a challenge when making something with so much potential to avoid the issue of scope creep and putting too much into it, it's like, ok, you want to make a game about pirates, what exactly do you focus on as there's a million different things you could potentially put in it, same deal with the old west.
I think that was Ubisoft's fear with making a pirate game which is why they picked the Indian ocean as a setting (makes it stand out a bit more) and why they just wanted to focus on ship to ship combat for a start and work their way from there for any potential sequels once the ip's viability was established, but people just had to sperg out and whine and potentially sink the whole thing.
Now Ubisoft should have known it would happen and been a little more ambitious from the start, but people also shouldn't have whined so much, to avoid what's happened, scope creep sinking the whole thing.
Make no mistake I was disappointed too when the game was first announced and it was only ship to ship combat, but while people can give me as much shit as they want, finishing what they showed in 2017/2018 is 100% what they should have done.