I'm not exactly sure what the fuss is about being able to Ajaxively quick reply. I mean, it's bound to bring more problems than it solves.
e.g., I'm posting a new reply, but someone's answered in the meantime. Should I show the post before, and draw your attention to it? Maybe I'll work on that in the future, but unless I'm paid for the job...
Also, if you post a reply on a page that has 15 replies already, you'll end up with your post on that page. Say you now want to share your post with
followers friends. Instead of copying the permalink, you copy the page's URL. And voilà, your friends will NOT see the post you meant to show them, because it's on the following page, not that one.