Step Loss On Failed Morale Check

[J6A]

I do not totally understand the change, either.  My guess is that it has to do with communications breakdown.  I have guessed (although I'm not sure) that the lower stacking limit is because units spread out more because communications is easier with modern equipment (note that irregulars can stack 3 high because they need to be in closer formation).  So, when a unit gets demoralized, its spread out all over the place, and units become combat ineffective more quickly.

Or, it could be something completely different.