Through a Glass Darkly

It's interesting to see how different translators render 1 Corinthians 13:12, which sits near the end of the 'Lurve chapter' of the Bible.

~ 21st Century King James Version

For now we see through a glass, darkly, but then face to face. Now I know in part; but then shall I know, even as also I am known.


~ New International Version

Now we see but a poor reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known.


~ English Standard Version

For now we see in a mirror dimly, but then face to face. Now I know in part; then I shall know fully, even as I have been fully known.


~ Holman Christian Standard Bible

For now we see indistinctly, as in a mirror, but then face to face.
Now I know in part, but then I will know fully, as I am fully known.


~ Darby Bible

For we see now through a dim window obscurely, but then face to face; now I know partially, but then I shall know according as I also have been known.


~ Weymouth New Testament

For the present we see things as if in a mirror, and are puzzled; but then we shall see them face to face. For the present the knowledge I gain is imperfect; but then I shall know fully, even as I am fully known.

The traditional and contemporary KJV versions sound beautiful and poignant: "For now we see through a glass, darkly, but then face to face. " So much so that the expression "Through a Glass Darkly" has been borrowed by film, music and literature.

So why have other translations opted for less poetic turns of phrase?

Is it for ease of understanding? Is "through a glass darkly" less comprehensible and accessible than "through a mirror dimly" or "indistinctly, as in a mirror"?

Why "mirror" instead of "glass"? Are translators able to choose things of the same nature (i.e. since mirrors are made of glass, they are interchangeable terms)? When "mirror" supplants "glass", is a different point being made (about self-reflection rather than perception or blurred vision)?

Here it is for Greek geeks:

βλέπομεν γὰρ ἄρτι δι᾿ ἐσόπτρου ἐν αἰνίγματι, τότε δὲ πρόσωπον πρὸς πρόσωπον· ἄρτι γινώσκω ἐκ μέρους, τότε δὲ ἐπιγνώσομαι καθὼς καὶ ἐπεγνώσθην,