Mismanagement of thrust may well have played a role but as others have pointed out the different flying characteristics when a big aircraft like the 321 is empty probably also contributed. I found the aircraft pleasant to land, but was always conscious of the potential for tail strike. Perhaps because people tend to be more aware of this risk I have heard that there are actually a lower number of tail strikes on the 321 than on the shorter 320. Nonetheless the concern might well have led the pilot flying to limit his elevator input. Anyway we will find out in due course.