That's a pretty common restriction on total file size for a small profile pic/icon not unique to here by any means.
The thing is, the forum software is supposed to be able to resize and reduce file size of oversized images to make them into user avatars. It seems to fail at some unknown resolution of picture (and larger), however. For example, if someone tries to upload a 1024x768 picture fresh from their digital camera as their avatar, the site is
supposed to accept the upload, resize the image into something much smaller, and then make it into the user's avatar. Instead, it just can't seem to handle files that are larger than ___?____.
It works perfectly with "medium" sized pictures -- it'll resize them down and it works great, but there's a point where it can't handle larger images.
Not a huge deal, as there are alternatives as I mentioned in my reply (#5) above, so I'm not rushing to try and debug the thing. I'm not a hardcore programmer at all, but more of a geeky end user.