It's funny you say that. That's actually why I choose Horde side and a Troll for my first toon. When I read the website, the Orcs were misplaced and struggling to survive in a strange world. I instantly liked that concept of being the underdog. Then I read the Troll story and fell in love with it. Plus the Jamaican accent was totally awesome.
Now the tables have reversed and the Alliance are losing ground.
Oh boy. :) Now you done it. Time for me to explain how I've spent the last 20 years interpreting the lore (Which I will freely admit, I might be wrong about.)
See, the Horde have NEVER been the underdogs. Back in Warcraft 1, a human (this will be a reoccurring theme, watch out for it) opened a portal because a Mad God told him to, and let loose the original Horde, a demon blood drunk and willingly corrupted race of man beasts we were told called themselves the Orcs. And they proceeded to lay waste to the human world of Azeroth.
In the second game the beleaguered humans decided they had enough of these green skins stomping around on their world and decided to take the fight back to them. By going back to the world that the Orcs came from. And sent their best to do it.Which they promptly close the door behind them, stranding their elite force behind the portal. There's more to it than that, but if you played through Burning Crusade it pretty much gives you the entirety of the Horde's side.
Now starts Warcraft 3. Where the Orcs are listless and almost lifeless as their drug supply (Demons' blood) ran out years ago. Out of this comes Thrall, the future saviour of the entire planet of Azeroth, but as we have all played WoW, I will not touch that there. So the game begins with Thrall breaking out his fellow homies from the human internment camps, which by the way, is a much more merciful treatment that most people would have liked, and frankly, the Orcs merited, as a certain Admiral Proudmoore believed. He wanders about the countryside until hearing about this new continent! Well, hey! Let's go there! There's no humans!
Now, you might be fooled into thinking that the Orcs are the underdog here, but not really. Once they've gotten their pep talk by human raised Thrall, the tribes go and lay claim to the land of Kalimdor. Along the way, they find and rescue the Dark Spear tribe of Trolls (Possibly the only mildly benevolent tribe left in all of Azeroth), giving them a new home. They find the spiritual, and potentially doomed (And they should have been...) Tauren, who were being wiped out by the Centaur. Yes, that race of incestuous morons that you slaughter by the cruise ship load during the beginning quests in Kalimdor. (Don't know about you, but to the Tauren... Darwin sez, YOU LOSE! Good bye! Try again next mutation!) Everything is looking great for the Horde! Two new allies, a new home! Yeah, Grom Hellscream had a bit of a back slide into his drug habit, but he got better, in the most AWESOME way possible. (Grom is my hero. :) I still have his axe in my bank. I use it to reskin any axe I get in WoW.)
The Alliance on the other hand, they're getting screwed. First, the Scourge comes back, awakened by the Burning Legion who decided that the Orcs were a waste of time and skin, as they couldn't do Sargeras' will, having failed, not once, but TWICE. (Mannoroth, nice guy that he is, decides to give them a second chance, and we know how well the Orcs thanked him for that.) So, the human Prince, wannabe Paladin does the RIGHT THING (Yes, culling Strathholme was the ONLY thing anyone could do. It was a lost city, NO ONE was able to be saved) instead Uther Lightbringer has an idiot moment, and denounces Arthas. Unfortunately, Arthas goes nuts in the process. Gets an Evil Rune Sword for his trouble, reawakens a Horde Lich, and comes home to kill Daddy.
Worse, he succeeds. Now, if you keep playing the human campaign, you find out that every single victory you get in there gets totally and completely undone by the Scourge campaign you play IMMEDIATELY after the human one. Everything you did in the previous campaign, literally, means nothing. The humans LOST. Gilneas isolates itself, to protect from the falling of Lorderon. Which becomes a undead infested hell, even after Sylvannas splits off from the rest of the Scourge, she pretty much still IS Scourge. After all, creating a plague to kill all life, to 'protect' her people is incredibly similar to what the Scourge wants to do to ALL life on Azeroth! So all the humans have left is a SINGLE kingdom, Stormwind.
Th Dwarves aren't better off. They lost one of the royal heirs of their kingdom to Arthas' quest. They have a traitor in the form of their princess (Whom I advocate killing her AND her spawn, because she WORSHIPS THE BURNING LEGION! And thinks that because she's the Princess she should be allowed to rule all Dwarves.) The Gnomes, the Wiley. E. Coyote SUUUPAH Genius that they are, literally NUKE their home, and still fail to kick out the invading Troggs. The High Elves, despondent at losing their Sunwell go nuts, and the Humans are suddenly racist, and decide to kick out their longest standing allies. The ones that TAUGHT THEM MAGIC IN THE FIRST PLACE!
Hell, even the Night Elves are screwed as their Life Tree got torched before they could stop the Burning Legion. And they lost their immortality out of it. Ouch.
So, let's recap.
Now the Orcs have a bright future ahead of themselves. They have new friends, a new home and are stronger now than they were when they invaded Azeroth about 60 years ago. They even kicked their drug habit! Their future is the brightest.
The Humans on the other hand have lost an ally, and most of their own that are still here have their own problems (Titan curses, Werewolf infestation), they lost several of their greatest heroes (even if Uther went stupid on them, during the Culling of Strath), and even more went corrupt, some even became more Scourge. The Humans are on the decline. 90% of Azeroth's current problem are Alliance made, in one way or another. Why? Often because of ONE person.
So no, the Orcs are not, and have never been, the underdog. The humans are. Which is why I play Alliance.