It seems the more we see outwardly, the less we see inwardly? Some thoughts on the nature of the veil.
I suggest that details in the accounts show that Joseph Smith experienced theosis or divinization in the First Vision, realizing his Oneness in God, or Christ living in him.
The "Urim & Thummim" were perhaps Joseph's own eyes, which in a mystical state of consciousness could "see" the visionary "plates." He lost these "gifts" for a time.