It's a valid point, downvoters. I think that having to ask permission to link an image inline is pretty silly - the responsible thing to do would be to rehost it in some manner and then link the rehosted version.
Screwed if you do (accused of breaking "copyright"), screwed if you dont (accused of "stealing" bandwidth).
I guess I don't see how copyright applies to publicly viewable images online that are being used for non-commercial purposes. Certainly someone can link to that page, and anyone could see the image. It seems to come down to "credit", and there should be a link to the original content.
The internet is pretty much built around the idea of finding interesting things in other places online and then sharing that. In fact, Google made a very profitable business just following and index those links to other content. The point of pinterest is to share interesting visual pieces. So a textual link doesn't do as much as showing a thumbnail. But it's still the same basic concept. Just as blogs expose links to interesting articles, so too does pinterest expose interesting pictures. In both cases, if you like the original what you see, you should be able to visit the original author/creator's page to check out more.
I see this as about as reasonable as blocking links on a blog. Don't publish articles online if you don't want people to link to them. Don't publish photos online if you don't want people to link to them (or share smaller thumbnails). If someone takes your article/photo and claims credit for it, then you have a valid argument. But if someone's whole "crime" is to enjoy your content enough to share it and advertise for you, a "thank you" would be more appropriate than arguing that they're infringing your copyright.
Copyright does apply (but only because they copy the image - even if a scaled version - to their servers and serve from there). Whether it should is a different issue.
