A tiny, simple RDM Request

[Rongway]

As Dualcast is the key mechanic of the job, an indicator on the job gauge would not be out of place.

Sometimes I cast one spell, get Dualcast, and have to move because of an AoE or maybe I have enough mana to do some melee attacks or something, and I end up forgetting that I have Dualcast in the heat of the battle and end up wasting it on something stupid like Jolt.

But why haven't you already pressed the button for the second spell before the first even finished casting, so that it cast immediately?
Movement doesn't affect Dualcast, and weaponskills cancel Dualcast, so in either case you shouldn't have a residual Dualcast lying around.