// What's the point in leveling up another job if you are just going to spend all of your Myth on your main job and then use that job to do your 1 run a week Coil run?//

which is why I always say to my self that it's better to just make a whole new character if planning to make an alt, and yes this I believe you raised a strong point, cross classing is only useful for the cross class buffs.