Of course arquebuses and muskets were cowards weapons. But they were effective. Oda Nobunaga rose to great heights after grasping the tactical power of gunpowder weapons.

The fact is that the game takes liberties with the historical facts in order to make for a better playing experience. If we wanted realistic armies, we would all have armies that consisted of 90% Yari Ashigaru.

I'm sure nobody wants that

(although I once beat an opponent who had large numbers of monks by using honour 7 & 8 YA )