The concept of being able to access your ancestor's memories was a cool idea and seemed actually plausible...in a sci-fi kind of way
The notion of changing history (if I'm remembering correctly?
) kind of killed the narrative for me. I thought the memories should be treated strictly as an unchangeable historical record: You could access it, but not use it to manipulate things outside the confines of what the ancestors did.
In terms of gameplay nothing would change. You'd still be free to go about things the way you want. It's just that the "way you want", happens to be exactly what "historically happened".
It's a fine distinction, but I hope I'm making sense.
By the time Black Flag came along, I could care less about all the Abstergo stuff. I just wanted to be a pirate.