Excessive Ground Time
 

I have often wondered why some long haul aircraft arrive early morning and then sit all day before returning. I have always assumed that it is for passenger convenience or airport opening times etc., but the economics of flying time versus waiting time must outweigh this. Surely people will still fly a longhaul route regardless of the time of departure and arrival.

Think about crew rest and you'd be closer to the mark... then there're airport slots at departure station and arrival station to think of and codeshare connecting flights and so on and so on...;)

Passenger safety at Arrival/ departure airport is a consideration. You don't want to arrive somewhere with a crime problem during night time hours.

Plus availability of public transport at certain time s of the night can be an issue

The most likely reason is that that aircraft would be turned around on a different sector, quite often we get 747s/777s turned around typically within 4-5 hours in comparison with short haul flights which are turned around within even half an hour.