most of the time they take up the entire shoutbox and they aren't necessary. people can just click the link if they wanna see the image, shouldn't be involuntary. we also have a media and videos channel for stuff like this. edit: ok guys there's joking around and then there's just being mean :'(
Might I suggest the following alternative: Instead of banning the images, maybe just put a limit on how many pixels tall and wide the images may be? Hopefully this can be seen as a slight compromise.