"By now the Transportation Safety Board must have a pretty good idea of why AC624 crashed"
Exactly. All this talk about MDA/DA/'hard floors'/'add 50ft'/'Dive and drive' is really irrelevant here.
The a/c hit the ground BELOW the threshold elevation and short of it. Regardless of 'limits', there was either a lack of visual reference and/or some sort of performance issue, either of which will already be known.