Yes of course below 0% is especially bad, but I dont think thats the whole story. If central banks were able to set inflation with 100% certainty I still think targeting a number close to 0% is a bad idea. Nominal interest rates have a floor due to defaults, servicing costs. As inflation approaches 0 that floor is hit and monetary policy loses its ability to control real interest rates. Keeping nominal rates above their floor is key to ensuring small business can obtain liquidity, as the floor is approached it makes less sense for lenders to write small loans.

There are many other reasons a positive inflation rate is better than substantially near 0. One common complaint about inflation is that erodes real wages because nominal wages are sticky, but this is actually a good thing. It gives businesses room to breathe during downturns without cutting nominal wages or having to cut staff. Positive inflation also forces cash into productive uses which helps monetary policy because it keeps the actaul money supply more stable.