Loft of the iron is only one variable. With the modern designs and clubhead materials , some of these lower lofted irons launch the ball higher than their more traditionally lofted counterparts. The result - higher ball speeds, higher trajectory and greater carry distance.
The study Result I posted a few weeks back comparing 4 different 7irons with lofts ranging from 30 to 35 degrees showed little deviation in launch and the lowest lofted club @ 30* produced the highest peak height and the longest carry.