Is it a good idea to create an artificial scarcity of risk-free debt in the euro zone?

The world is chronically in a situation of ( ex-ante ) excess savings and strong demand for risk-free bonds. The euro zone also has a structural situation of excess savings and a preference for risk-free assets. When the ECB, through its purchases of public debt, reduces the amount of public debt available to investors/savers, it then creates an artificial scarcity of risk-free bonds when demand is strong. The result then is: Abnormally low (negative) long-term interest rates; A forced switch by savers to riskier assets, which do not match their preferences, and therefore probably a loss of well-being.