As a general stand point, it based on team setup, tactics pick and priorities. The attack prioritize of most basics focus top down so a tank or off tank in top row with something like sailor Sakura in bottom back so all ninjas in middle and top go for the tank first. Another is position choice since its set as front to back and top to bottom, thus a first position on the bottom needs to be either front most of the row, or in mid with all others in back.

I agree with the decision being based on the team setup, chosen tactic and the priorities. Now a days I rarely fight anyone that puts their ninjas in the top row. That would be one thing that would contribute to me saying that using the top row is not needed.