Suggestion: WHM change

[Katoar]

Why would I ever hold onto all these stacks to use a heal over time when I have a superfluous amount of heals in my kit already and can instead go for Spiritual Ray or Seraph Strike? Why would I ever go for Seraph Strike if building up to Spiritual Ray does more overall potency?

You are not going to use all five stacks to go for Spiritual Ray right of the bat as this will leave you at 1HP with 50% reduced max hp for a considerable amount of time. Tornado, Water III, Earthquake and Spiritual Ray are spells that cost Enduring Faith stacks. These stacks are obtainable only when Blissful Sacrifice is active.

Spiritual Ray is a channel with extended GCD recast time to prevent people from using Swiftcast for it. A channel as it allows for slow movement which allows adjustment.

Again, why? Why am I killing myself to do my basic DPS rotation?

Healers prefer to manage HP bars. As WHM arguably has no resource management, choosing HP to be the resource they manage in order to get the best out of the job, doesn't seem too outlandish to me.

Where am I getting all these free Faith stacks from?

Benediction
Type: Ability
Cooldown: 30sec
Cast: Instant
Range: 25y
Radius: 15y
Effect: Cleanses all debuffs on nearby party members.
Additional effect: Applies five stacks of Blissful Sacrifice to self for 5 seconds.
Blissful Sacrifice: Upon activation, extends remaining duration by 5 seconds, afflicts 20% of max hp damage to self and simultaneously reduces max hp by 10% while under the effect of Blissful Sacrifice. Gains 2 stacks of Enduring Faith.
Enduring Faith: Allows for the execution of Exaltation, Tornado, Flood/Water III and Earthquake. Effect expires with Blissful Sacrifice.

Wind + Earth takes 7 stacks of Faith. You get 2 stacks every 30 seconds from Benediction.

No, you do not get 2 stacks every 30 seconds. You can get between 0 and 10.

Making one of White Mages GCD's take longer serves no purpose and doesn't fit its identity

As WHM has no identity or if it has one it is Glare, I do not see a problem in suggesting or giving a new one. The game initially portrays you as some sort of conjurer who is attuned to the forces of nature and uses them to defeat adversaries and heal allies. And then as you level up White mage becomes that sparkly white girl out of nowhere.
WHM has no unique traits. Benediction is an old and outdated oGCD that has outlived its purpose and value. AST has the same cooldown and AoE version of it.

[fulminating]

Even dark knight isn't this aggressively self-damaging and that's the job most associated with trading hp for damage in the final fantasy series.