bwwaaahhhh!
Face faking is great for putting **28** in pornographic situations, etc. Here, we tend to mostly be interested in giving girls bigger boobs.
It's usually alot easier to just fake the chest. Faking a face brings many challenges. The worst being the hair! Hair matching is a bitch.
The second culprit is the proportioning. When making a breast morph, the goal is to make the boobs disproportionate, how disproportionate is up to the artist. When doing a face fake, the face MUST be in proportion with the new body. It takes lots of figiting, and playing around. Eventually you find a suitable size; only to look at the picture a day later, the head still seems out of proportion.
Third is positioning. Sometimes the head you want is in a slightly off positon, this means the neck is also involved. An intricate amount of attention must be payed on the neck, and muscles involved.
Fourth, is highlights and shadows. If the lighting source is in a different angle between the face and new body, you need to drop in highlights. In this aspect, a face is harder to work with than a boob. A boob is realtively a smooth sphere, very easy to hightlight and drop shadows. A face has all these little bumps and valleys that would affect lighting.
Fifth, is what you originally touched on. It's more satisfying to leave as much of the origianl subject as possible. If I'm doing a Lacey Chabert morph, I want to see Lacey. Her awsome legs and hot hips and back... just with bigger boobs.