From the perspective of a college freshman, I am tempted to think I would love to have an infallible memory. I could easily remember every due date and every snippet of lecture on command - or the name of that girl I met during welcome week with the cute smile who I haven't been able to talk to since. We have to wonder then, why it is that we all don't have memories like those of "the woman who can't forget?"
Well, for one, In the story of Ms. Price it is clear that her ability to recall things so well is derived from an acute importance she assigns to her memories. She has assigned so much value to the past that she has had to prioritize it over other things. In a sense, she has imprisoned herself in the task of curating her own life.
The trade-off seems to derive from the limited capability of humans to store and retrieve information and process it at the same time. Perhaps somewhere along the evolutionary tree there was a nexus where two humans with equal-sized brains, one with the better ability to predict the future and process the present, and one with the better ability to store and retrieve information from the past, were faced with a survival situation in which the present-focused human survived. Maybe this type of situation happened a few thousand or hundred-thousand times.
That hypothetical model might demonstrate how lack of perfect memory might have persisted in humans to "make room for" other, more useful, thinking traits. But then again there are times when good memory may mean the difference between life and death. Once again though, the brain seems to be well-suited to its purpose. Traumatic events are often the most difficult for people to forget. Also run-ins with scary animals or threatening situations seem to illicit a particularly strong imprint on memory - just ask anyone who has been afraid of dogs ever since being bitten as a child, for instance.
The author states that anyone could have a memory like that of Ms. Price, all it takes is consistent dedication and effort. But you may end up sacrificing things, such as your ability to go out and explore new things, or to live in the present and seize opportunity to get that way. And when you commit every detail to memory, you end up with a lot of useless or painful baggage. So the real question seems to be -- would you want to have a perfect memory, or would you prefer to just have good memories?