Hmm. I think adding a warning to an image page that reminds people not to use the image on article pages where it wouldn't be appropriate or otherwise minimize it to 100px (and explain how to do this because image formatting can be scary if you haven't done it before) is a good idea. I just thought we were talking about something different when the idea of templates was introduced. However, it it's just a warning anyway, there is no need to include the complete warning text on the article page. If the image has been minimized, you can see that right there, there es no need to add an explanatory text.