According to this article, four prime-ministers from EU issued warnings about EU disintegration after Jean-Claude Juncker talked about the possibility of having a "multi-speed Europe":
Prime ministers of four central European countries warned against the "disintegration" of the EU a day after European Commission president Jean-Claude Juncker outlined possible scenarios for the future of the bloc, including a multi-speed Europe.
According to Wikipedia (the article has several issues, but I think it is still relevant for an overview), there are many non-uniformities within EU: Schengen area Treaty, European Defense initiative, European Constitution not being ratified by some national parliaments.
Other arguments for a multi-speed Europe include:
- the Poles have opted out of the Charter of Fundamental Rights
- the Czechs keep them company outside the Fiscal Compact
- justice and corruption problems in Romania and Bulgaria which forced EU into having Cooperation and Verification Mechanism (still active after more than 10 years of membership)
Question: Why is multi-speed Europe frowned upon if reality seems to confirm the concept?