If it's a "print" do not add changing images. Now we have on first slot "Passport Photos" story with plinking photos, which makes me wanna click X ASAP...
This is likely down to a simple oversight when loading images from articles. OP probably didn't consider GIF images. I don't think its a choice that was made to add animated images. @OP - you can use Cloudinary to transform images on the fly (also stops you using other sites resources) to fix this issue easily.