I don't really think it's the same, no. I can understand what you're saying, but the United States started off as kind of a blank slate and we just kept adding and combining different kinds of people and backgrounds as we went along. However the countries of Europe have been independent nations for generations - hundreds of years for many of them, and most of them have their own culture, language, customs, differences of religion, etc. Each one is different - France is different from England is different from Germany is different from Poland is different from Italy and so forth. I don't see how they can combine all these different cultures under one govt umbrella without losing their power and identity.
However your argument does have some merit to me. I would not have opposed cessation of the South had I lived during those Civil War days. I think a state should be allowed to leave. I'm obviously in the minority and I had both sides of my family fight that issue (on opposing sides). I do believe the growth of Federalism and a centralized govt does indeed threaten the liberty of the individual citizen as the govt grows further and further beyond his or her control to manage or change. The govt, even on a state level, has become the province of lifelong bureaucrats and policitians who make this their life work instead of the part-time avocation and civic duty I think the founders intended it to be. This professional government has become an institution and power until itself and fairly impervious to control by the citizenry. That is a very bad thing. The smallest and most local govt generally is the best for the ordinary citizen.