I think I understand Rare's vision for this game, seeing how they don't want save zones, they don't want to classify weapons in a system that makes some better than others, I think Rare wants a true game that shows real realism. there are no overpowered people in this world, only people with more experience and knowledge, therefore you are much more stronger in the game if you played for longer than a player that just started, just because you know more. There are no main stories/quests because you make your own legend. many games have tried using the "make your own story" marketing strategy and might, or might not, have made the game without a concrete main story, but I think they are taking a right step in making a game where your voyages truly define you.
Thanks to this video I now see that this holds more truth, since the higher you are in a trading company the greater of a name you will have for yourself, this probably is that you will have a title as a pirate (something commonly known that pirates did, I will try my hardest to be a pirate king).
Just know this, I was really hyped when the game was announced, then i lost that hype since i didn't see anything new showing up, after playing the alpha and testing its "core" mechanics (remember it is core), I can confidently say i enjoyed it all the way, heck i would buy it just for its core mechanics, but it doesn't mean it would do well with just that. The game lacks the marketing of information, i'm sure they have great stuff, but we don't even have hints of it.
As for the leveling, i don't see why we need to level up our characters, this game feels rather innovative. I think we need to go in with an open mind expecting systems which we would normally see as unethical in the aspect of game design. The word sandbox is a good description of this game, is not a typical sandbox where you create the world but one where you shape your character around the world it self.
P.S: Rare, the thing missing before you even release this game is letting your fan base understand what its your objective for the players. We barely know much about the game and if we don't understand how you want us to feel or what position to take while analyzing your game people will be unable to agree with themselves whilst taking sides.