There are millions of these memes all over DA and the Internet. You gonna write to everyone and ask them to take them all down? I don't see George Lucas complaining--or the owners of Grumpy Cat, who are millionaires now thanks to some sweet book and toy deals.
They shouldn't be all over dA. I don't care if they're on other sites on the internet, as long as they aren't posted on ART sites. This is an ART site, and when you post something to this site, you are CLAIMING IT as your work (unless you've got written permission to use someone else's, which you don't), so no, I'm not going to ask everyone all over the internet to take their memes down. But for every meme I come across on an ART site, I WILL ask that it is taken down, as someone who respects the original artist/photographer.