I cannot tell you how many times I've been loading Alla on a semi-slow or unstable connection and come into a thread with a lot of images that loaded slowly. Because the images don't have width/height tags on them, the browser doesn't reserve the space necessary for them, so when I'm trying to read a post, it's constantly getting bumped all over the place as the images load one by one and force the browser to resize the content to make room for the newly loaded image.
It's really annoying. Let's get the width/height tags on there, mmkay?