Particularly in the LA, flaming short bows aren't really an offensive weapon, they're a deterrent. They say, "I've got 12 volleys of flaming death waiting for you behind my walls. Perhaps you should look elsewhere." And Bogarus needs its neighbors looking elsewhere until ~year 4.
Agema was looking for an obvious troop tactic. 8g archers + flaming arrows seemed obvious to me.
I dont really understand the fuss about 2.5% chance for F3 starets. F2 is enough to cast flaming arrows as long as you have phoenix power and an extra gem, afaik.