Merits are more of an illusion of choice. For a lot of jobs, there's simply stuff that's good and stuff that isn't. While this philosophy really wouldn't change even if all spells and abilities were naturally progressed, if we had a generic Slow potency+, for example, it could make both the T1 and T2 versions better if for whatever reason you're being more frugal about your MP or alternating between timers due to fast kills or even resists.
Anyway, I wouldn't use /SCH if the intent was to mainly melee, either. Though, if I'm out in the field and melee wouldn't result in party wipe, there shouldn't be miles of difference between /SCH and /NIN or /WAR. Giving up Dual Wield or Berserk/Aggressor/DA/ATK Bonus is bad enough, but losing out on EX WS is just more salt on the wound.
