I just got a fresh install of Illustrator CC and every time I place a raster image into my document, it appears dim or very light. When I go to export the image, the PNG file displays the image correctly.
Double-clicking on the layer only brings up a dialogue box to change the title, and two checkboxes: "Show" and "Lock". "Dim Images 50%" isn't in there.
For what it's worth, I remember previous versions of Illustrator having that option. The Template option used to lock and dim the image, but I'm not seeing that anymore.