This is an excellent idea. For me, Pinterest ruins search in a few ways. First up. I don't have a Pinterest account. This means when I click an image result I can't actually get to the full-size image without logging in. Second, since all their content is stolen the original source of the image is pushed way down in the results (if it's in there at all). Finally, I get the feeling there are a lot of bot created Pinterest boards as images tend to be shown beside completely unrelated images.
This is not a big problem, but it is annoying enough that I downloaded the extension. I'd like to see a Firefox extension, too.
I have been making little JavaScript extensions to do things like sift eBay results and remove sponsored links from searches on some sites. None are mainstream, but they are used and useful.