Not really sure why anyone would suggest that raise casters are 'protected'. If you look at the fastest clears, there are two fights where RDM and SMN have 0% representation. That's even worse than MCH. BLM isn't much better off, but at least there are a few dedicated fans that optimise on it purely for the sake of challenging themselves. Meanwhile PCT has a lock on the caster slot, with up to 98% representation in some cases. That's not a caster slot, it's a PCT slot. The caster role is a mess right now. And I say that as someone who remembers Stormblood tanking.

And this outcome is predictable. Because you're effectively trading off 10% of your damage output for that raise. RDM/SMN have a role to play in initial progression when you're trying to understand how a mechanic works, but outside of that you're going to prefer to replace them.

Now if you buffed SMN and RDM to PCT levels, something interesting happens. You wouldn't replace a melee slot, you would replace the Physical Ranged slot. Because the DPS difference that PCT provides makes up for the 1% inclusion bonus. All of these scenarios are bad.

Standardize access to raise on ranged jobs. Give them all DPS parity. Let players bring the ranged jobs that they like. Bring the player, not the job.