You are adamant in demonizing Ulfric aren't you? If major political party A in the US was allowing a foreign power to dictate our lives and send their men to kidnap religious people, I'd fully support party B in a civil war.
Ulfric wasn't found to be less popular.
You conveniently ignore several issues, such as the Empire doing everything it can to ignore enforcing the Talos ban
until Ulfric started making a fuss about it to draw Thalmor attention. As typical of a stormcloak, you confuse the Empire with the Thalmor and lash out at something that was about to launch a campaign against them, as part Tullius and Rikkes dialogue, and just like a typical stormcloak you are short-sighted to an extreme. Nazi Germany just conquered the world and invaded the US, occupying most of it and only after an exceptionally bloody campaign is pushed out in a phyric victory, only for the next wave to be poised to land. It's far better to stall for time until we could mass produce nuclear weapons and delivery platforms for them, than become a province and ruled with their iron fist. But no, destroying ourselves because the government lost a war is such a better logical choice, and to top it off he most powerful state would be leaving and putting the entire country in a significantly worse position while the nazis gain strength. You might as well apply for a job in the Thalmor embassy, because that should would be going along with their plan hook-line and sinker.