Is HTML tags good or bad for forums?

I think HTML is good in general - it means you can, for example, upload images to make your discussion more interesting/accurate/informational. However there would be some debate as to the limit on pictures, they could seriously slow the site down. And then we've got to go into the "how big should a picture be" thing, and if its small enough to ensure accurate running of the site - is it worth having the pictures at all. I'm not sure how to directly relate it to this site - I dont know what the bandwith thingy of it is. But if its big enough to cope with the things that HTML can do, then it'd be a great feature!