One seldomly hears vB5 and professional in the same sentence
However, on topic: In my opinion, comments on posts make it much harder to follow threads, actually. Imagine a 25 page thread. So, now someone comments on a post on page 20. How do you find that post? What will be shown on the main forum index as last post in that thread - the actual last post, or the last comment on a post? The read/unread system and how it works will not allow you to count comments on posts as unread, or, if you find a way around that: if you read said comment on page 20, it will automatically mark all new posts after page 20 as read. And I'm only just beginning. Comments on posts disturb every discover-new-content-functionality vB offers - as on display on vb.com with vB5.
Yeah me personally I can't stand it either, this is a forum, not Facebook.