Maybe so, but that's exactly what I'm arguing. Ulfric is doing the exact same thing people criticize the Empire of. He isn't fighting to free Skyrim, he's fighting to control it. Two very different things.
Of course he's fighting for control, in the sense that *someone* will have to rule Skryim once the Empire is out of the picture. But a Skyrim that is ruled solely by a High King elected by a Moot of other local rulers who are not beholden to a foreign power is a whole different thing than a Skyrim ultimately controlled by an Empire for which Skryim is not "home" but, when push comes to shove, just a valuable military and economic asset. (Whether or not you agree with that assessment of the Empire's interest in Skyrim is irrelevant, as those who want the Empire out *do* indicate that they believe exactly that and it's part of their motivation for seeking independence.) He
is fighting to free Skyrim from Imperial rule. That it will then be ruled by someone else, whether it's Ulfric or not, is a given. You don't fight and win a war for independence and then say to your countrymen, oh well, you're all free now, everybody just go about your business and solve your own problems however you like because nobody's in charge any more.

You might just as well say that the US founding fathers weren't fighting for independence from Britain, but rather for control of the former colonies because they really just wanted to run things for themselves. Well, yeah, they
did want to run things themselves, that was kinda the whole point of the revolution.