I mostly agree that the results are not always good. As someone who read the original style transfer paper, and implemented it, I disagree that it is applying a mechanical effect. Maybe I'm biased but the algorithm use a pre-trained CNN on object recognition. The CNN develops a representation of the image that is more and more abstract along the layers of the network. You can visualize the information in each layer by reconstructing the image only from the feature maps. And when you do this you will see that the network, learns the objects and textures of the image compared to its pixel values (pixels -> edges -> regions -> objects, etc).