Especially after I found the two settings needed to make this look and behave like a standard linear-view forum.
1) Under General Settings scroll down to "Thread View Options" section and for "Thread Display Mode" select "Linear - Oldest First". This sets how a thread is displayed when you've clicked on it. It does not impact the thread listing.
2) Scroll further down the General Settings to the "Miscellaneous Options" section and for "Forum Skin" select "Topic View (Classic vBulletin)". This will give you a list of only the first post / topic titles instead of the branched/threaded view on the main page for the forum.