One of the reasons was that our old toolkit had several shortcomings. Some instruments were not available, or could only be used in limited ways. These shortcomings became very clear when Dutch financial group SNS REAAL, ran into problems in 2013. The government had to step in, and the banking and insurance group was nationalized.
From my point of view, it is vital for the new member countries to perform catching-up real growth that permits their income-per-capita levels to gradually approach the average income level in the present EU member countries.