Good and Evil is a point of view. True evil is those who do terrible things which they think are good. Is Ulfric evil? No. Do I support him and the Stormcloaks? No.
Ulfric's cause is a good one but misguided, how would Skyrim rule itself if one man can kill another and claim their title, the strong and arrogant will rule over the smart and weak, if a Bandit chief can simply walk into a Jarl's longhouse and challenge them to a duel in the old way they'd have to accept and the title will be passed onto the victor. How many Jarls and Kings will change hands during Ulfrics reign and after his reign, that anyone with a sword can simply challenge the ruler of Skyrim and claim the throne. With Imperial rule that cannot happen.
Yes the Empire surrendered and that so shocked the nords saying "When the Empire surrendered they shamed us all" The Empire didn't simply roll over they took the Thalmor head on and took the war to a stand still, their capital in flames they could not continue the war without protecting those within their border from bandits and beasts, you do not fight a war if you can't maintain the supply lines due to having to leave men behind to guard cities and roads, they wouldn't have much of an army for the front lines, the Empire signed a PEACE TREATY they didn't simply lay down their weapons, the Thalmor are more talk than bite with "The Empire lives because we allow it" they got heavy losses in the war same with the Empire.
Hammerfell fought off the Thalmor why can't the Empire? Hammerfell fought off the Thalmor in their home land, terrain they have fought and lived in for hundreds of years, The Thalmor would still need supplies to maintain it's hold in Hammerfell and Redguards are tough mofo's, but you fight even harder when you're defending/retaking your home. The Empire would have to take the fight TO THE THALMOR they'd have to march onwards and take the fight to their homeland, well that is a little hard to do with less than half strength, the Empire isn't as weak anymore they have had quite sometime to rebuild their Military, the Civil War in skyrim is only being handled by the IV Legion under the command of General Tullius and he isn't being given reinforcements so I'd say he's doing one hell of a job considering he CAPTURED Ulfric the great man who is fighting the Empire because they "Surrendered" to the Thalmor, well he surrendered to the Empire when he was captured, only lived because of a Dragon popped up.
And that Talos thing being such a big deal, the Nords use to hate Tiber Septim and fought against him it wasn't until he defeated them that they betrayed the Bretons and joined Tiber Septim.
I think what the Emperor did was smart, what would you do if you had less than half your strength, your capital burning and to keep fighting you'd have to march out of your own lands into the heart of the enemy. The Empire didn't even enforce the Talos ban they didn't even care about it, they sent gold to the Jarls of Skyrim to keep it quiet for awhile, but smart Ulfric decided he'd stir up trouble MAKING the Thalmor step in, The Empire couldn't simply attack the Thalmor with Ulfric messing around, he killed the High King of Skyrim then ran like a bat out of hell out of Solitude.