Is one photo/wallpaper/screencap/icon worth as much as one link?

No one (*) knows how the different content is weighted, though I agree with your sentiment.

Other content is often "worth" more, as far as the depth of the information provided for the club's topic, but 图片 are the most likely item to get a rating of any type of content. This is because it takes the least time to evaluate an image - 你 don't have to read anything 或者 watch anything like a video 或者 a link. I think this latter is the main reason that heavy image posting seems to get "rewarded" with 更多 奖章 than a similarly heavy posting of other content: they're just getting rated more.

* Aside from the 潮流粉丝俱乐部 staff, presumably.