You are a random guy who never heard about the franchise. You see it in the store. What do you think the game is about? Is it a game about assassinations and planning how to take out a target? The meaning of the word they decided to use as a title and therefore the main focus of the marketing would imply that.

You can also look up the devblogs and interviews for AC1, where Patrice Desilets always talked about how he wants to make you feel like an assassin and how it is about social stealth and stalking your target to plan your assassination... in not a single word did he ever mention ship battles...

And now you say somebody else doesn't understand the mechanics and their purpose? The thing here is, when you look up the development focus of the different AC games you will notice that big fights and so on were never the focus in the first place. They only suddenly switched to that when they saw how their improved fighting system got a lot of people into the series. And what followed was a complete disregard and stagnation of the very social stealth system they used during AC1 to sell the game. To make you feel like an assassin.

Just because you like the direction it took doesn't mean, that the franchise was ever thought to become like this or should be like this.