The ECB’s forward guidance The ECB first introduced forward guidance into its introductory statements at the press conference in July 2013, saying that it “expects the key ECB interest rates to remain at present or lower levels for an extended period of time". This is also referred to as expansionary bias with respect to interest rates.
There are worries about the desperate search for yield. Or fears of a banking crisis when interest rates will increase because banks are reacting to the ongoing low interest rate policy by increasing maturity transformation, which increases interest rate risk. Your question seems to imply that low interest rates are bad but higher interest rates are also bad.