I would not expect modest changes in the output gap to exert more than a marginal influence on inflation. But the anticipated slower pace of growth will result in an environment in which firms will be less able to pass on increases in costs. One potential source of higher costs comes from the labor market.
Credibility in monetary policy requires clear targets, so that the aims and objectives of the ECB can be explained ex ante and the implementation of those aims can be explained ex post. A clear target is an important means of achieving transparency and accountability, i.e. of communicating with the financial markets, policy-makers and the general public.