We're creatures of asymmetry. We're loss-averse. And we're not particularly rational, a lot of the time.
So, to be able to do things like real-terms wage reductions, it's much easier to implement a freeze in nominal wages within an environment of positive inflation, than nominal reductions within an environment of zero inflation. So some inflation allows for relative and absolute adjustments in remuneration of different jobs.
But too much inflation creates too much uncertainty and instability.
So, 2-3% is currently considered to be "goldilocks" inflation within developed economies: neither too much, nor too little, but just right. Other places, and other times, have had different ideas.