The ECB unleashed the fresh stimulus to combat risks ranging from the China-led slowdown in emerging market economies to the slump in the price of oil. Speaking in his office at the Bundesbank's Frankfurt headquarters, a few miles north-west of the ECB, Mr Weidmann said the debate ahead of Britain's vote on whether to leave the EU had added to "the mood of uncertainty" within the bloc.
Uncertainty about the future of European integration, illustrated by the Brexit debate and the difficulties in finding a solution to the influx of refugees, could delay business investment both in the the UK and elsewhere. "The uncertainty adds more weight to the option of shelving plans for a later date," the Bundesbank president said.
Brexit could also fuel the current mood against more EU economic integration. "It could lead more people to ignore the very fundamental insight that, in a globalised world, the answer to the challenges is not more fragmentation," he said. "That doesn't mean you have to centralise everything. But in a union you have to seek joint solutions and ensure the liability principle."
While it would "not be a very smart move" for remaining members to punish a departing UK by erecting barriers to trade, the outcome of any post-Brexit negotiations would be political, and so very difficult to judge.
"When you follow some of the debates that are taking place in Europe and in other parts of the world these days, you have the feeling that, deplorably, a more inward-looking approach is often the response to the challenges of globalisation," Mr Weidmann said.
Plans to impose limitations on cash payments, as mooted by Mr Schäuble, and abolish the €500 note — a move favoured by some of the ECB's top officials — could further sour the public mood in Europe's largest economy. Many Germans fear there is a hidden agenda to abolish cash altogether.
"So far the evidence I've seen is not really convincing that the financing of terrorism or illegal activities can be countered by limiting cash payments or abolishing the €500 bill," Mr Weidmann said. "Even in the US, where the highest denomination is the $100 bill, some would like to see this note abolished. So there is no telling where this debate would end."The Bundesbank president downplayed tensions between the International Monetary Fund and other players in the Greek crisis, at odds over whether to haircut the member state's debt. While Berlin opposes further debt relief for Athens, the IMF favours it, and is considering leaving the rescue team if it does not get its way.
"The debt burden is less of an issue than the question of whether Greece is capable of achieving a sustainable fiscal surplus or of implementing the structural reforms necessary for growth," he said. "As long as the programme conditionality is not adhered to, debt relief will be of limited use: we would just end up in the same place in a couple of years' time."