Exactly. Even Desmond had this ability but he just didn't knew how to use that.
But what AC4 didn't discuss is that all the previous games showed that even precursor genes are not enough to make you an assassin, that's why Ezio's brother was executed so easily, same with his sister, she wasn't an assassin and his father was more like a scholar, so he also got executed easily by thugs and Ezio nearly died trying to save is family, he learned blocking, climbing etc throughout the game, later on he could take a dozen guards unarmed, so you need training to become assassin, same with Connor, he learned fighting like all other Native Americans, but learned Assassin fighting techniques later or(the game din't do a good job with this, he was powerful from the start, there was no actual growth, like how Ezio actually became strong by learning techniques).
But Kenway was strong from the start, he killed an assassin on his first encounter, an assassin who had been training for his entire life to become what he was then, then inexplicably he knew all assassin techniques from start(air assassination etc), there was no growth, kenway was as strong in game as he was at start, there was no growth, the only thing that grew was his enormous ego and his ship, that's it, the story was completely disconnected from the Assassin vs Templer storyline, AC4 is all respect was like COD, no story, no character growth, nothing, it feels like a multiplayer ship battle, with a dumb AI.
I have some more gripes:
The ship battle grows tiring after some time, the game has no replayability, I played AC2 3-4 times, see how things would turn out once I knew all the kicks, how I could tackle situations a bit differently, there is no such thing with AC4, you see ship, charge ship, fire some cannons/mortars, board, rinse and repeat, there are no angles there, soon you would have tried all possible combinations of taking out a ship, so where's the fun?
Even Games like Mass Effect 2 allows you to replay with all powers and upgraded to see how you tackle situations with all powers unlocked, same with Borderlands 1/2, other games like the witcher 2 has a complete alternate storyline, some games like fallout has so many damn explorable areas and random encounters that you would keep going back, some games like Binary Domain/Gears of War draws you with storyline, but AC4 get repetitive over time.