The thing is that the game should not focus on the War if they don't intend for a faction to win over the other. Siege of Orgrimmar was an example where should they have followed reality the Horde would have been dismantled. Other things that gameplay trumps over lore is when they severely nerf a faction that has so many advantages it should be a stomp just to give the other a fighting chance by simply removing them from the picture or worse yet ignoring their existence. In reality Garrosh would have never been Warchief. In reality Garrosh should have lost his life in various moments of idiotic decisions that he took.In reality neutral factions who act for the protection of Azeroth should have declared war the moment a Warchief went nuts and started destroying things left and right or straight up attacking them to obtain something. Who knows what would happen if the Dragon Soul wasn't sent back to the past. The same goes for the new Warchief that is getting her hands on every weapon possible even something related to the Old Gods. In reality a faction consisting of nearly extinct races and starving would be hard to suddenly provide unlimited supplies, armies and warmachines when they can't even feed themselves. Finally in reality the various characters would be more smart to not support Sylvannas in her new war attempt not after how the last one ended. Saurfang would have decapitated her the moment she proposed a new war and definately any of them would have challenged her into a Makgora after Teldrassil and tried to fix things.
But to be back on topic what is the point if I forgive the Horde or not. Blizzard will force my character to forgive the Horde.