has always let the admin determine the max height/width/filesize allowed for attached avatars. this is an option which is useful for forums run on home servers or are on other such limited bandwidth settings. in 2017, webhosts offer much more than they ever did in 2005.
feel free to update your stock avatar, and to update the settings on your forums to match this current generation of websites. also feel free to notify your users if you update your forum settings.
you have the power to customise and run your forums the way you want.
this software's stock options were set in an attempt to more closely adhere to 2017 based forum standards.
in addition - you can also choose to not allow users to upload their own images, but instead let them use a stock set of images you provide to them.
you can also let them link to their own hosted image. i believe that gizmo links to his facebook profile image. and on several ubbt forums im a member of, i link to my set of 25 coffee/gyn themed randomly rotating 250px x 250px png self-hosted images.
in ubbt 758, gizmos and mine images could push the left/right column or the post list profile column off the screen, or the image would have a distorted presentation. this is not an issue in 760.