Notification counts should update automatically. I shouldn't have to reload the page to see if if or how many new notifications I have.
Support for inline Markdown or BBcode, so that my hands don't have to leave the keyboard to format my post.
Faster response/loading times. That I notice any delay should be an embarrassment for the likes of Google.
Much higher density listings, to include at least the topic's subject line, last update time, original poster's name or avatar, and most recent poster's name or avatar. View count, post count, like count, tags, and snippet are much less important.
Auto-loading of more content when I scroll to the bottom of already-loaded content. I shouldn't have to click anything to load more.
When entering a previously-seen topic, take me to the oldest post I've not yet seen. I shouldn't have to search for where I left off.
Keyboard shortcuts everywhere.
Less white space. It serves no purpose. It's a waste of perfectly usable screen.
Hide user settings that have no effect. Why are they even exposed? Are you even aware they're there?
More function, less form. Design for the real-world users, not for the implementation team's academic idealists.