I also don't see lists that are as long as I remember in some forums.
By default, each forum's index page is set to display topics active in the last month. Since the posting activity at FTM has been much quieter in the past month than in the first couple of months, there may literally be fewer threads displayed in that default list than in the same forum, say, six weeks ago.
You can display a different time frame's worth of posts by making another choice in the Show Topics pop-up menu at the bottom left of a forum's index page.