I'm surprised that Create Trap is that low, but the actual order of things doesn't surprise me in the least.
#1 Alchemy is niche but killer when applicable, allowing people to build up usable stockpiles without being broke all the time.
#2 Blacksmithing is needed for any chapter that uses tons of arrows or has Giant Armor Tanks. Anyone who wants to Fast Refit all the time without rituals is gonna have several ranks of this skill.
#3 Scrolls are possibly the best general-applicable offensive reserve production item. Alchemy requires a metabolism, Potions have a ritual requirement, and Traps have limited effects.
#4 Potions will probably always be about here. If they had a better Mastery ability, they might even beat Scrolls.
#5 Great pocket reserve resource, but too limited in choices and too expensive to regularly use, and while I'm sure every chapter or nearly every chapter has That Trap Person, the tediousness of traps really cuts their draw.