Can we see a reason why the ECB should raise its interest rates?

The ECB has announced that it will not start raising its interest rates before the summer of 2019. Can we see a reason why this choice would be a mistake, a reason why the ECB should raise its interest rates now? Wage inflation remains low in the euro zone despite companies’ major hiring difficulties; core inflation should therefore also remain low, as the current inflation mainly stems from the oil price; Financial imbalances ( excessive debt , asset price bubbles ) concern only public debt (excluding Germany); private debt has been declining since the crisis, we cannot see any signs of equity market or real estate bubbles at present ; Risk premia have since the second quarter of 2018 returned to a more normal level due to the rise in risk aversion. If we look only at core inflation, financial imbalances and the level of risk premia (after the recent correction in these premia), there is no urgency for the ECB to raise its interest rates. But a very powerful argument remains in favour of raising interest rates: the euro-zone unemployment rate is probably close to the structural unemployment rate; if the ECB does not raise its interest rates, it will be unable to lower them when the next recession is triggered. It is this quite simplistic argument that is driving the Federal Reserve to raise its interest rates.