div class="postfootleft" should immediately follow div class="postleft" in viewtopic.php, so that stylesheets can put div class="postleft" and div class="postfootleft" together. They should be adjacent in the document tree because a user's status is closely associated with that user's other information. In fact, "postfootleft" should probably be a child of "postleft", but that change is riskier than just making them siblings.
Currently div class="postfootleft" follows div class="postright", which makes it harder to use stylesheets to reposition it, because it cannot join flow with "postleft" in certain ways.
PunBB should use HTML for structure and leave presentation for stylesheets. Therefore the div and other elements should be organized structurally based on how different things relate to each other, such as a user and their online status, rather than organized according to layout.
Example of a site which has "postfootleft" following "postleft" but looks the same as default. With stylesheets alone after "postfootleft" is changed to follow "postleft", the site can be completely changed to look like this.