This is definitely wrong. They are indeed the representatives of the people who gave them majorities in the national votes. Because of the national constitutions those representatives have the duty to protect the national interests and to decide about such matters. Since a EU membership is in the direct interest of practically all European nations, the practical decision for the European leaders is easy. Democracy is a relative concept. Such contrary concepts like communist "democratic centralism" and direct democracy are labeled as democracy. Many people in the western word are in the dumb belief that their own national concept would be the one that provides the maximal possible freedom, although such simplification is usually wrong. Due to the fact that we Europeans (btw. just like you Americans) do not have the better direct democracies fixed in our constitutions (except of Switzerland) we are forced to live and work with the existing body. Direct democracy would delegate the decision about such fundamental matters directly to the sovereign, the people of a nation. In a imperfect representative democracy the decision about those matters is given to the elected representatives. Exactly this happened in Europe concerning the new EU treaty.
You see - all of us still have to work and fight for more freedom. BTW - do not be offened. I know that the United States relies on representative democracy, but its system of government is much more complex than that. It is not a simple representative democracy, but a constitutional republic in which majority rule is tempered by minority rights protected by law. Things are complex, but i.e. the decision whether a comparable treaty would be signed or not by the US lies in the hands of your president as the representative of your people. Therefore your system would not be better in this concern than the systems in Europe.
As I said - freedom and democracy are relative concepts.
P.S.
More European solutions in all concerns are from my point of view simply a basic exigence. You may think different here, but the practical needs within Europe are facts and can not be delayed just because we are unable to find perfect national solutions for democracy. This means we have to deal with the existent structures. It might be possible that there are areas in Europe that are not that dependent to a greater Europe like the quarter I live in. We Germans in the south-west are closely interwoven with the Swiss, the Austrians and the French in all concerns. Our neighbors are ethnically closer to us than i.e. Germans from Berlin or Magdeburg. The German national concept does not fit into our needs anymore. Therefore it is quite logical to us to look over the boarders. Believe it or not but within western Europe there are indeed majorities for a closer relationship. The thing is that most people there are afraid of the Europeans from the east and their impact on our societies. The recent vote against the EU-constitution in France i.e. was more a vote against Chirac and his plan to associate the Turks.
The EU gives me open boarders, a common currency and the right to vote i.e. in other European countries if I have my residence there. Furthermore we established a powerful common market that makes us far more independent from other nations than we ever were before. More than 50% of the German exports go to other European countries. Furthermore we were able to find European solutions to reestablish large scale industries and technologies what would have been impossible for a sole nation. Airbus, ESA, EADS, Eurofighter, GALILEO or ARIANE might not be in the interest of the US, but they are for sure in our well understood own interest of European nations. I could extend this list for hours but I am aware that such is not political correct in a conservative US forum. ;)
“The EU gives me open boarders, a common currency and the right to vote i.e. in other European countries if I have my residence there.”
But why does the EU have to involve itself in domestic issues of the member states like abortion and immigration?
Why can’t the EU simply be an economic entity that protects against free trade from outside the bloc, why does it have to be a political union?
The over zealous regulations over domestic issues is what makes Americans wonder why Continental Europeans think the EU is a good thing. An economic union makes more sense in the view of Americans.