I respect that as I come from a text-mostly low-level hacking background. But don't you notice the mouse cursor changes when it hovers over the pictures? Also the shadows and backgrounds of click-able pictures resemble buttons (smooth round edges.) Apple is famous for working very hard on perfecting the user experience.

Yes I do notice, but for some reason the cursor isn't enough. I probably assume it will unpleasantly popup a larger picture of the same.