As soon as you start Skyrim, you are immediatly involved in Skyrim's Civil War and are forced to choose sides. If you choose the Stormcloaks, then you made the right decision and acted on honor and integrity. The Empire, at the beginning of Skyrim, was trying to execute your character, a presumably innocent bystander, in order to enforce their corrupt laws estabished by the Thalmor. The Empire are nothing but the puppets of the Thalmor, too weak to protect themselves, their people, and their faith. So are the Stormcloaks, or rather Ulfric. Remember he was captured by the Thalmor at one point and it is heavily implied the they planted the idea of rebellion in his head. Divide and conquer, basic military strategy. Get your enemy to start fighting each other, and swoop in after one side has destroyed the other, or they stop fighting because all resources have been exhausted. You never offer a treaty to someone if you are perfectly capable of beating them completely and then forcing them to do something, so the White Gold Concordant was the Thalmor way of biding time until they could weaken the Empire. The events in Skyrim is probably just one of many ways of doing so. Talos, who in Elder Scrolls Lore is actually a God, united all of Tamriel and ascended to godhood. The jealous Thalmor made Talos worship punishable by death in order to preserve their elven superiority. Actually, before Talos was raised to godhood there were only 8 Divines. This was simply a return to the Alessian Pantheon established at the beginning of the second Era. The corruption of the empire is seen immediatly when that Imperial Officer orders you to the headsman's block without mercy or consideration of your innocence. You are sent to the block because you were caught with a stormcloak patrol, with Ulfric no less. They cannot verify that you are not really one of them, so they are forced to execute you to be sure. But I'm with you there that the reasoning is still a little sketchy. Standing with Ulfric and the Stormcloaks is the right decision because you are ultimatly overthrowing a corrupt empire in order to overthrow the tyranni of the Aldmeri Dominion and safeguarding Skyrim from oppression as Ysgramor did before you. Even though the Stormcloaks are racist against non-nords at the beginning, the Empire is much worse because the Aldmeri Dominion are willing to order ethnic cleansings to ensure that Mer are the dominant race. The Stormcloaks force the Dark Elves to live in a slum because they are foreigners. Guards get away with extortion and bullying against other races. The Empire has created a system of near equality for all the races, or did before the Great War. The Thalmor want to see the Mer on top, they don't hide that. When push comes to shove, the Empire will be the greatest enemy they have. If you are a race other than Nord and complete the Stormcloak campaign, you basically prove to all of Skyrim that the other races are not inferior and must be treated with respect. They don't give a crap if you fight for the Stormcloaks. Nothing changes in their view, you just become an exception. Ulfric Stormcloak killed Toryg in fair combat. Toryg could have declined the dual and stepped down from the throw if he chose it. Ulfric misused the Voice. It is not a tool to be used to gain power or influence, it is a gift that is meant to be used to protect. It would be like bringing a gun to a fist fight, you just don't do it. Ulfric knew that, and so did the rest of Skyrim. That is why he called a murderer, because he brought the Voice to what was supposed to be a regular duel. Rogvir was still executed to opening the door for Ulfric even though niether Ulfric nor Rogvir committed a crime. In conclusion, supporting the Stormcloaks is not treason. How can it be treason when the Thalmor(and the twisted remnants of the Empire) are not sovereign over Skyrim?
Playing as a race other than Nords (especially one of the Beast folk or elves) and siding with the Stormcloaks would be like playing as a Good Karma woman in FNV and siding with the Legion. It just doesn't make any sense.
EDIT: After posting this I noticed that there are 5 pages of discussion. I feel dumb now. Forgive me guys, I've been up the past three days now playing Skyrim. (I accidentally deleted my entire Skyrim folder on the 360, 1100 hours out the window).