User blog comment:JoshofBlades/Why the Empire Should Prevail Over the Stormcloaks! Part 3 (Economics)/@comment-4098609-20111123001855/@comment-4113369-20111123145754

Well, if they declared independence it wouldn't even be an option. They would be invaded faster than you can say "Silly, short-sighted, racist Ulfric". And while there are a lot of adjectives there, it still doesn't take very long to say. And the Thalmor use other races as slaves, so an invasion would be... bad, to say the least.