I'm not sure I follow your response correctly, but it seems like your response is:  it's easy to switch image sizes this way.  But you still have to edit the HTML, and it's not that hard to edit the width/height.  Maybe I don't understand?<p>The more important point to my mind is that grey is definitely not lorem-ipsum.  It doesn't help me evaluate anything except image size.  And since it's easy to get a sized placeholder, a server to generate a URL seems not that helpful.