Some have complained of the large benefit the Shadow Player gains by having limitless reinforcement potential while the Free People have limits. One can, however, readily argue that Orcs and Uruk-Hai can be quickly bred/created as the need arises. For the Southron/Easterling forces, however, this argument loses weight. This proposal removes some of the Shadow Player advantage in this regard and should create some more interesting dynamics on troop usage.
BALANCE OPTION: Limited Evil Men
When Southron/Easterling units are destroyed, they are removed permanently from the game, in the same manner as Free Peoples troops. All rules regarding removal due to stacking, reduction of Elites to Regulars, etc. for Southron/Easterling units follow the same rules as Free Peoples units.
It's an interesting suggestion. I've only played four times but I've found you really only have time to build one large army of Haradrim/Easterlings (each) during the game. By the time you send them in and resolve the battle, you won't have time to build another force if disaster strikes. I guess it would be handy to bring them back if the FP gets feisty and takes the attack to you!