Casting

[Gruntler]

Ok I see you point I was more leaning on the side of them not having a GCD and how would that play out. Though I didn't think about RDM that would screw them up pretty bad. Overall I was just trying to understand and see why and you guys certainly helped with that. Thank you I will think more into this.

It would remove most of their rotation and change it to Verthunder/Veraero.

That'd be an awesome cooldown to have, for a short window, but it'd be awful as a core rotation.

[Gruntler]

Your best way to look at cast would be... The ranged role.

In HW they had 1.5s cast, low enough to weave, high enough to make the GCD feels like having an impact.
The problem is that BRD was not designed to work with casts while MCH was.

So they removed it in SB for both BRD and MCH.
It did wonders for BRD but MCH... Its kit made no sense anymore. Which is why they had to remove a lot of MCH kit from SB to ShB.

Even if SB MCH would have an overheat button during SB it would have remained a boring job during filler phases.

If you were to remove casts from casters, many tools would not make sense anymore.
BLM Leylines would feel weaker, its triple cast would be useless thunder stack would be extra damage only.
SMN ruins and extra ruin would be useless.

MCH was not made to work with casts, it was optimal to only have your gauss barrel on for gauss round (three ogcds to do one damage ogcd is good play?) and for wildfire (when rapid fire made you not have a cast time anyways.)

[Stepjam]

Different casters have different cast times and multiple casters have instant casts.

For an example of both, BLM both has a few casts that are longer than the GCD (Fire aspected Flare is the main one that comes to mind) but it also has the ability to instant cast any spell (such as fire aspected flare). So you need both cast time and GCD.

A few casters have some casts that are actually faster than the cast timer, like Astro's attack spell. And you don't want to get rid of the GCD for them because that small period can be used for movement, since optimally you want to be casting GCD after GCD, so without that small period, they'd have less time to move, an issue WHM has.

[Grimoire-M]

MCH was not made to work with casts, it was optimal to only have your gauss barrel on for gauss round (three ogcds to do one damage ogcd is good play?) and for wildfire (when rapid fire made you not have a cast time anyways.)

Machinist’s Combo-like procs bypassed the cast time last I recall which meant, in fact, it was a mistake to take it off ever. Ammo made their RNG reliable enough in practice to rarely need to move.

[CaesarCV]

I think that another part of the reason Casters have the charge times is to, well, make them feel like spellcasters. Ranged and Melee DPS classes don't have cast times, at least now they don't *glares at HW Wanderer's Minuet*. When you play a Spellcaster, you want to feel that glorious rush of power as a spell goes off at just the right moment, or the terror of an enemy approaching while you desperately make your incantations and such. Having casting bars helps bring that feel into Caster classes and helps their identity compared to other roles.