Why is it that, in 2016, it’s STILL necessary to retopo manually in most cases?
There are tools out there to make it easier(RetopoFlow). If it was some kind of magical, automatic operation people would be complaining that it doesn’t do what they want.
There are some people out there trying to create solutions for automatic retopology. But even professional solutions would find it hard to interpret exactly what you expect from the end result. I imagine some manual input is always going to be necessary for organic models. Especially if they’re intended for animation.