Getting back different tier spells?

[Elexia]

How often did you actually ever cast a previous-tier spell in XI?

No, we don't need tiers.

Depends. In Abyssea tier III > IV > aga (aoe tiers) were used heavily. In Voidwatch all tiers are used. WHM/SCH/RDM curing will use III/IV/V/VI depending on situation. BLUs will use different tier debuffs depending on situation. While leveling you'll use different tiers as it is what's available to you at the time and so on.

This game can use tier spells even if they scale, because Cure > Cura > Curaga isn't really enough cure spells when you think long term, breaking it up to Cure > Cura > Cura II then Curaga > Curasa for AoE tiers work fine. While Curaga works on less hp > more healed, it's really an "oh shit" spell since the only optimal cure spell will generally be locked down on recast whereas if we had multiple you could cycle through it incase of emergences (since most encounters you only have 1 benediction.)

[Firon]

Depends. In Abyssea tier III > IV > aga (aoe tiers) were used heavily. In Voidwatch all tiers are used. WHM/SCH/RDM curing will use III/IV/V/VI depending on situation. BLUs will use different tier debuffs depending on situation. While leveling you'll use different tiers as it is what's available to you at the time and so on.

This game can use tier spells even if they scale, because Cure > Cura > Curaga isn't really enough cure spells when you think long term, breaking it up to Cure > Cura > Cura II then Curaga > Curasa for AoE tiers work fine. While Curaga works on less hp > more healed, it's really an "oh shit" spell since the only optimal cure spell will generally be locked down on recast whereas if we had multiple you could cycle through it incase of emergences (since most encounters you only have 1 benediction.)

The bold makes no sense seeing how spells scale with your lvl meaning that Cure will always be a effective spell at all levels means it better long term then lets say XI where cure 1 is pointless in anything but PL.

[Elexia]

The bold makes no sense seeing how spells scale with your lvl meaning that Cure will always be a effective spell at all levels means it better long term then lets say XI where cure 1 is pointless in anything but PL.

Cure does scale, but it's also fairly low even at cap since cura is much better than cure at cap for example, thus you're more likely to see cura used over cure. It's also two sided: You also need content balance to be taken into consideration, but having scaled skills doesn't really mean tiered spells can't exist, they'd just have higher caps while making sure none of the previous ones are pretty much worthless to use.

Just like in XI, tier IV nukes are still powerful even though tier V have higher caps and can hit much, much harder at times so you'd still actually use both for a viable source of damage.

[Firon]

Cure does scale, but it's also fairly low even at cap since cura is much better than cure at cap for example, thus you're more likely to see cura used over cure. It's also two sided: You also need content balance to be taken into consideration, but having scaled skills doesn't really mean tiered spells can't exist, they'd just have higher caps while making sure none of the previous ones are pretty much worthless to use.

Just like in XI, tier IV nukes are still powerful even though tier V have higher caps and can hit much, much harder at times so you'd still actually use both for a viable source of damage.

Cure right now in the current version is a good spell when healing in most fight you don't even need to spam Cura its just over kill.... Only time i cast Cura is when a boss does a ws all AA attacks from bosses can be healed up with Cure. Like i said Cure is very useful unlike if @ the start of the game where cure 1 was garbage as soon as you got cure 2 and was a waste of spell then so was cure 2 when you got cure 3.

[Yrusama]

Depends. In Abyssea tier III > IV > aga (aoe tiers) were used heavily. In Voidwatch all tiers are used. WHM/SCH/RDM curing will use III/IV/V/VI depending on situation. BLUs will use different tier debuffs depending on situation. While leveling you'll use different tiers as it is what's available to you at the time and so on.

This game can use tier spells even if they scale, because Cure > Cura > Curaga isn't really enough cure spells when you think long term, breaking it up to Cure > Cura > Cura II then Curaga > Curasa for AoE tiers work fine. While Curaga works on less hp > more healed, it's really an "oh shit" spell since the only optimal cure spell will generally be locked down on recast whereas if we had multiple you could cycle through it incase of emergences (since most encounters you only have 1 benediction.)

The system using suffixes goes beyond -Ra and -Ga. Like you said, there's Curasa, but there's also -Ja. Here's a list of all I've seen in the franchise:
-Normal/No Suffix (e.g. Fire, tier 1 fire spell)
-ra (e.g. Fira, tier 2 fire spell. Also for AoE versions of FFXI buffs, such as Protectra or Barfira)
-ga (e.g. Firaga, tier 3 fire spell, or AoE in FFXI)
-ja (e.g. Firaja, tier 4 fire spell, also does something weird in XI but I forgot it)
-na (e.g. Poisona, removes Poison status. We have Esuna as an all-purpose debuff remedy)
-sa (e.g. Curasa, heals HP in proportion to missing HP in FFXIII)

Correct me if I'm wrong, but I remember hearing that Materia in the Japanese version have tiers using this system:
Materia > Materira > Materida > Materiga. This opens up the possibility of more tiers, such as Materija and Materisa (V and VI for EN players), which we may see after a level cap increase. Perhaps they could make Materina as a unique type that can alter/remove currently-melded materia. Not saying they should, but it's a thought.