Why the Horde is not considered bad in lore?

[Friendlyimmolation]

According to the novelization of "Beyond the Dark Portal," the Skull of Gul'dan seemed to corrupt Ner'zhul in some manner, whispering in his thoughts and driving him to heights of egomania and megalomania. Prior to its influence Ner'zhul was essentially a deathseeker almost completely immobilized by despair - although I'm sure Teron Gorefiend and Neltharion's influence weren't very helpful, either.

Yea, but it doesn't affect everyone, Grom laughed at it and the Laughingskull who gave it up to Khadgar to spite the horde didnt seem effected by it either. I think part of Ner'zhuls evil is that there was an evil part of him and he ends up embracing it. Was he effected by the skulll? Maybe.

[Inukashi]

There is so many villains on both sides and on other factions.. but none of them is a real villain by himself.

Nearly every crime goes back to the old gods, the titans or the legion, which a ruled by the titans greatest warrior.

Old gods
Ragnaros (servant of old gods)
Black Dragons (Deathwing was corrupted by the old gods)
Garrosh -> Jaina


Titans
Creating Sha by killing an old god
Sargeras going mad by other reasons
Sargers corrupting argus (Kil'Jaeden, Archimond and was close to also get Velen)
Sargeras took the Legion after fighting against them


The Legion
The Legion corrupting Gul'dan, Cho'gal, Arokka
The Legion creating the Scourge
The Legion losing control over the Scourge
The Legion semi corrupting Illidan to fight against the Scourge
The Scourge corrupting Arthas
Worgen created because Druids gone mad fighting satyrs/legion

Like every villain was created by the old gods or the titans fighting the old gods
If you count the legion to the titans failures you can bring everything to the old gods or titans.

The List of characters that aren't bad because of the Titans/old gods war is really small (Blackmoore, Zul'jin, and maybe some others...)

[Aucald]

Yea, but it doesn't affect everyone, Grom laughed at it and the Laughingskull who gave it up to Khadgar to spite the horde didnt seem effected by it either. I think part of Ner'zhuls evil is that there was an evil part of him and he ends up embracing it. Was he effected by the skulll? Maybe.

My personal theory is that it was essentially personal between the Skull and Ner'zhul. Gul'dan knew Ner'zhul of old, having been his apprentice in Shamanism and his successor as the nominal chieftain of the Shadowmoon Clan after Ner'zhul refused to carry out Kil'jaeden's will after the events at Oshu'gun. He would've been perversely delighted in having a posthumous chance to corrupt Ner'zhul and turn him against first the Horde and then all of Draenor, and finally delivering him into the hands of the Legion. Gul'dan didn't know either Khadgar or Grom very well, and Grom being a warrior wouldn't have the sensitivity to magic to recognize the Skull as anything but a grisly token. The seeds of egoism and pride were definitely present in Ner'zhul, as that was how Kil'jaeden was able to manipulate him in the first place, but I think his ultimate fate got a lot of assists from outside forces bent on destroying him.