Terrible compared to what alternatives? Showing images at half their expected size? On a Retina screen, images have to be scaled up somehow.
For non-Retina-aware apps, MacOS just scales the entire window up by a factor of 2. Being Retina-aware means for things we can scale intelligently (text, vector graphics) we do much better. For images we usually can't do much better although at least we give the author some control (choosing between nearest-neighbour and bilinear scaling via the image-rendering CSS property).