Maybe we could rotate them twice per day, giving each FA 12 hours on the main page. Then we wouldn't be increasing the amount of clutter there. The first screenful is the most important thing, many readers will never scroll down when they visit that page.
That would result in people that only check the front page once a day (which is probably a very large number of people) missing half the featured articles. It would be roughly equivalent to having the featured article chosen at random from two options a day each time the page is loaded. I think that would detract from the concept a daily FA.