Well, I see. Thank for the replies. But it all sounds like "Well, there is a better house around the corner, but we'll stick to this rather good one." When you edited WP to add tags or other features, did you say "this would mean changing this and that and something is/might be outdated, so no chance"?
Threaded comments (thanks for the better word) give so much more convenience to commenters. This allows to reply directly to one of maybe a hundred comments. Both the commenter and the one whose comment is replied to can clearly see everything.
I have one post in my blog with 51 comments - the biggest number for me so far, but quite a low figure in comparison to many other blogs. Every time a new comment appears only after the latest one. If there are different threads or lines of conversation, people have to scroll and scan through all the comments and it is so much easier to lose this thread or get tired of adding "re this comment" or "to Mr/Ms X:".
I do not mean to show disrespect or suggest that WP is a bad blog system. In fact I advise it to my friends and people around as the one giving more flexibility in one's side panel, more themes and more professionally looking ones at that. But without threaded comments it feels like still in its adolescence. :-)