The trouble with melta, though, is that it was (and still is) a very high-risk proposition: get really close to the big bad and *hope* you wipe it out before it gets you.
With the removal of any realistic chance of an instant kill, melta gets dealt a serious blow. Safer and more reliable to stack LCs, stand back, and blast away.
I mean, sure, we'll still see melta about, but it's supremacy as a tank-killer has just been seriously undermined. The upside, of course, is that now Melta is going to make MCs sweat, whereas before they were largely unimportant.