I think the point is that the existing large-scale federalist states are all conceived as top-down: a central authority makes (most of) the rules, and lower rings have to suck it up.
The European project is supposed to be a bottom-up, consensus-driven setup where each member-state brings its best contributions and persuades the others to "level up". That's how the best EU directives were born.
In a way, even the Euro was something like that, with Germany persuading others that a "common Deutschmark" was a superior setup for the common currency they had agreed to implement (in exchange for letting them re-annexe East Germany); and overall it was, at the time, when compared to weak inflation-ridden and debt-burdened currencies like the Franc, the Lira and so on. The problem is that circumstances change, and the German model turned out to be very inflexible for economies that significantly differ from the German one. So now a consensus is emerging that the setup needs changing. A similar situation in the US or Australia would be fixed with a few decrees and simple majorities; in the EU that would be unacceptable. Alliances and majorities have to be built from the ground up, and they have to conceive a compromise that will satisfy most member states.
The south didn't vote for Lincoln and attempted to secede with the US president initiating the war to overturn the local state's right to do so.
I think a lot of europe's problems would be fixed by making the office of the EU presidency a directly elected office in a similar fashion to the US presidency. The EU would still require further centralization to maintain the eurozone and to further deepen the EU single market. They are just required to maintain our current levels of wealth and to fix the banking crisis that has never really been solved in the EU.
A single individual with a policy platform that has gained legitimacy through campaigning in all EU member states would settle questions related to the future of the union and will be best placed to implement and direct policies that benefit the majority of the EU population.
If you consider that the US took 4 generations to unify and you consider that present-day it is hard to imagine a peaceful unification then you should also consider that the way you think about things is dramatically different then the way your grandchildrens' children will perceive things.
For example, currently a large part of the EU population speaks english as second language but it's hard to imagine that majority of voting-age EU population to not speak english as second language in 80 years from now.
Speaking a single language will probably clear the biggest hurdle for effective political union.
But even many of my European friends who favor these things seem to not agree that that's the inevitable vector that these institutions point to. I'm certainly not saying that the system will mirror the U.S. system, but it certainly will end being a system like this if Europe continues on the present unification course.
Is there some nuance of the direction that I don't understand? It seems like as every crisis comes to Europe, advocates of pro-Europe seem to continue to point to centralization and empowerment of a single over-arching European government.