why is the texture color is pink rather than the image file is not missed
you can see the image file name in node 
You can usually tell your image is missing if you go to the image editor and try selecting your image from the drop down menu and nothing shows up. That means Blender has all the data of the image, the name, location, etc, but the image is just not where it knew it to be, it can't find it. And yes, Blender needs a better system to tell you there image is missing.
