It makes more sense than levelling up did in DA:O. My warden somehow increased his innate strength fivefold over the course of a few months, and he was already a trained fighter to being with.
Having that massive boost to strength comes from enchanted armour is far more logical...
Finally somebody who can agree with me on the silliness we put up with in RPG's sometimes. Seriously, who beleives that because Randomwarden Cousland killed 70 darkspawn, he suddenly learned how to bash stuff in the head with his shield, and also gained 1 STR, 1 CON and 1 DEX. By extension, killing a million darkspawn must turn you into a god or something.
The inquisitor is made of multiple parts. Like a real book a movie character he has a supporting cast, and tools he uses to overcome challenges. he is not a perfect human being, and he is not a juggernaught in combat just because he killed a thousand men. He has his talents, and magical gear and the resources of the inquisition to augment those.
EDIT: the above paragraph actually kinda made me think of shepard, funnily enough