Personally I didn't think of it as an option, yes you might have natural fat in it, but you can potentially lose it, also, the most important thing, shape. the shape is very difficult to get it right, and ive seen some who had it, and they don't look particularly good.
I mean, nowadays BA can work great aesthetically and look totally natural, if natural is what you are after. but still, aeshetically speaking, they look far better than fat grafted breasts.