Why does mages have to choose between 4 stats and other just 3

[AttacKat]

Why does mages, SCH/WMH/SMN/BLM, have to choose between PIE, DET, SS, or CRIT while melee just choose between DET, CRIT and SS. Why not add some gear for melee that dont have VIT?

Hmm, I always choose just one stat per class/job, that one stat that your class trait enhances.