There is no need for multiple spells or multiple tiers, it might feels like you have more choice but it was never that way, there has always been only that choice of spells you'll use. It only gave you the illusion of freedom.

Easy example from XI or could be used for XIV,
Protect & Shell -> Wall
1238193819-na's -> Esuna
1231973719 Threnodies -> Threnody that reduce all magic resistance?
Fire I/II/III/IV/V/VI/VII/VIII/IX -> Fire that scales with your level, omg!

and 15/11 limit is only for level50cap, there is no doubt this will change as they increase level cap.