Well CJW has decided not to tell us why displaced thresholds may be a difficulty, but others have. Well done.
It is of course illusionary, a fixation on landing phase, to the extent that the mind is telling you that the threshold is in fact the end of the Tarmac, not the clearly defined, white runway markings which as we all know indicates where the take off run should start, and the landing phase/flare may begin. In general, displacements are there for very good reason, normally that danger lurks prior to the runway beginning. Carlisle was a classic, can't remember which runway, but there was a fence, a wire fence that crossed the runway, I think laterally they put up big white crosses, but it would have ruined your day had you landed short of the threshold.
It may be that in this particular case, it was really as simple as being to low, and to slow, thinking that get it down on the Tarmac prior to the markings, and of course the trees came a bit too close.
Condolences to all involved.