If the threat is great enough, you learn to make common cause. I could cite some RL examples but there's too much of that already in this thread.
yes, and i could cite real life examples where the opposite happens. But, i agree, there's too much RL in here.
and yes, I agree, it's the intermediate officers have the biggest impact, don't get me wrong. But you can have multiple intermediate officers under one supreme commander.
and yes, there's still poor leadership, and no, such intermixing doesn't necessarily promote better cohesion, BUT:
1) poor leadership is one issue. The fewer the complications preventing an army from fighting effectively, the better. Plus, poor leadership can be replaced.
2) uniformity breeds a better soldier. Period. The more uniform and disperesed different groups are in a force, there's a greater chance (not a guarantee; we can make no guarantees here) that each man and woman will feel like part of a large body rather than a smaller group in a large body.
3) where's your proof that the empire is not doing so well at motivation outside of cyrodill? Where do we ever encounter Imperial officers who actually have some development other than Rikke and Tullius?