I've played the MSQ twice, once as a WHM and once as a MCH. To me, it almost felt like both my characters had different motivations for doing what they do.

WHMs are... sort of caretakers of the balance of nature. Conjurers more specifically are but as a WHM you came from Conjurers so that doesn't go away. So... my characters motivation was the wish to save the people she cared for and to preserve the delicate balance of the world that foes like Lahabrea would disrupt, and the Blessing of Light and the Elements both were empowering me to give me the strength to do what must be done. Even if what must be done is currently hurl rocks at something until it dies.

It should be noted that the elements don't really care about most things mortals do, so long as it doesn't disrupt the elements, so my character is free to use the strength they give me so long as I don't abuse it, and I continue to protect the balance. Thus I can do the random tasks people give me like hunting beasts for sport as its not something the elements care about.

As for MCH, well that one was pretty easy. A tech savvy gunner looking for adventure wherever she could find it, with a moral compass that lets her do the right thing when its needed most even if it means letting that wonderful looking adventure slip through her fingers.