That's not my experience as a German living and working in Portugal. Economic differences between countries will always exist, just like there are poorer and healthier regions within every country, but in daily life these play no role. Differences are superficial, people here and there share the same values and overall culture, and European countries are migrating rapidly towards each other in these terms.
Of course, not paying for structurally weak regions has always been a popular topic among the inhabitants of richer parts (see the Länderfinanzausgleich), but in the end this attitude is just selfish and unrealistic. The EU sceptics of today are the same kind of people who were against the unification of Germany yesterday. Let's all go to war with Prussia then.
That may be true, as far as cultural "western" values of democracy, liberty, secularism, etc go. However the vast gap between the economic standard of living of e.g. Germany and those of Portugal are a source of (justified) friction. The less wealthy states see themselves as subservient to Germany and the wealthier states, with no real power and no real say in how the (supposedly democratic) union is run.
That's not how the Portuguese see themselves and their role within the EU.
That being said, of course, there will always be friction, just like there is friction inside nations due to unequal distribution of wealth and structural disadvantages of certain regions. That was my point. Monetary transfers and other aid to certain regions are unavoidable unless you want to get into a vicious long-term downwards spiral. That's the same everywhere, whether in Europe, in China, or in the US. If you leave the economically weak countryside without any help and perspective, they'll turn against the rich regions some day or migrate towards them, and you've made things worse than if you transfer money right from the start and try to decentralize resources and services from the beginning.
Portugal is currently doing fine, but other countries don't do so well. There will always be a region that is not doing well. It is wholly unrealistic to expect this not to be the case within a union of any kind - whether it's a union of states/regions within a country or a union of nations.
Of course, not paying for structurally weak regions has always been a popular topic among the inhabitants of richer parts (see the Länderfinanzausgleich), but in the end this attitude is just selfish and unrealistic. The EU sceptics of today are the same kind of people who were against the unification of Germany yesterday. Let's all go to war with Prussia then.