Does the use of fats or sugars necessarily dictate the use of the direct-dough method? Surely this is too simplistic an analysis, but it seems that way.
I don't think it's dumb :)
I don't think it dictates the direct-method. I suspect it might be the other way around. Preferments and retarded doughs develop flavor without the use of additions to the dough, so the *lack* of added ingredients required the methods of preferments etc. to give you the flavor you want. Since I think added fats/sugars can kind of mask the more subtle flavors of sourdough or sponges, there's not as much to gain by indirect methods. Of course this is oversimplifying it a bit--as always in baking there are exceptions to every rule :)
However, I have retarded just about any type of bread, for convenience reasons. At the bakery I worked at, we made all of our doughs the day before (from baguettes to sandwich loaves), becuase it made production in the early mornings a bit easier--we could just shape and proof breads almost first thing in the am, and then make doughs later at a more leisurely pace. One thing to consider is reducing your yeast quantity slightly as they can overproof even in the refrigerator if you let them go too long.
I guess I always see a place for both indirect and direct methods. I certainly appreciate the quality of breads made with complex formulas, but some days I just want bread in 2 or 3 hours--or I want something to stick a hamburger in that doesn't really deserve an artisan fancy pants roll to go with it, ha ha.