I'm guessing their reasoning is that "serious" photographers don't go around taking cute pet pictures or something like that. It would definitely be a useful feature.
The autofocus on my EM10 II is pretty quick and accurate in most conditions, but the camera has a serious tendency to back focus when subjects are moving, especially toward the camera...no matter how fast the shutter speed is.
This holds true for face detection too. If the subject is moving at all, I never trust the face detection when it tells me it has focus. I usually resort to reducing the focus box to the smallest size and using the touchscreen to focus and shoot.