[Free movement] just needs to be worked out, not abandoned.
In principle, I agree with you.
However, "working it out" when you're starting with the level of disparity between countries like the UK and Germany on the one hand and the "new Europe" nations on the other is a generational problem that will take many years to solve. It's not something that can be finished in a matter of months with a quick treaty or two.
In the meantime, if you immediately establish tight integration as something like joining the EU does, you have artificially increased the pressure on both the weaker and the stronger nations. Consider that Greece -- which was already an EU member and part of the Eurozone -- is still in serious economic trouble today, coming up to seven years after the big crash. There are still serious political frictions there over dealings with Europe, and there are still serious political frictions in nations like Germany, where they have been picking up the tab for all that time.
One possible alternative is to provide humanitarian and economic aid to less fortunate nations without such close formal ties. For example, the UK has a government department responsible for international development. It has thousands of staff, and now sends over £10B per year in aid funding, mostly to nations across Africa, Asia and the Middle East. This makes the UK the #2 provider of official development aid (after the US) in absolute terms, and the #5 provider (after Norway, Sweden, Luxembourg, and Denmark) relative to gross national income.
So again, if the UK were no longer part of the EU, this doesn't necessarily mean the UK would no longer support the economic development of the "new Europe" states. A cynic might also point out that unlike the EU, there are also actual accounts showing where the money for UK overseas aid is really going and robust mechanisms for reporting and shutting down fraudulent claimants.
For the near future, this kind of arrangement might be more beneficial to the nations receiving the aid and impose a lower risk on the nations giving it, without the mechanics of shared currencies and the like clouding the issue. So again, looking at the big picture, I don't see much of an argument for the UK becoming more tightly integrated with the EU and in particular joining the Eurozone given the current economic disparity among member states.