Even more, big member states have to give up one of their Commissioners from 2005 on. Finally, each member state has one vote in the institution that decides on the general political direction of the EU, the European Council. All decisions have to be made by unanimity, therefore Luxembourg has the same influence in the European Council as the United Kingdom. The Treaty of Nice did not lead to a loss of influence for the small member states. This would have been impossible, since all the changes of the Treaty have to be decided unanimously.
Sovereignty is a strange animal.
A country deciding to join or stay out from a community of nations has the sovereign right to do so. But those two options have a different impact on sovereignty subsequently. Joining means enhancing sovereignty by taking part in the collective sovereignty of the more influential community. Staying out means to be faced with the consequences of decisions taken by others. From the moment of accession, however, it can influence any new decision by the Union.