OK, here it is:
1) High inflation is unstable inflation. Instability is bad for all humans (controllers and workers), as it means only every other generation gets to retire and the other have to be euthanized. So, high inflation (meaning roughly 10% and up) is extremely bad, and the closer you get to that the more unstable it is - so you would preferably be farther away from it.
2) Low (or negative) inflation is bad for typical worker humans. It is superficially the best for banks (controller humans), as the assets they are holding get more valuable. Long term, this is not true though - the controller humans are dependent on the worker humans, and so long term they have to allow them to get a good deal or no one will let them control anything. The most obvious downside to low or negative inflation is that debts become harder to pay off. A less obvious, but arguably more important downside is that instead of giving everyone constant raises (which make everyone feel good), any worker only performing "average" (as in half of all workers) has to have their pay cut each year (which makes them feel bad). Not that the silly humans would actually be making the same amount either way (in hamburger buying power, for example), but for whatever reason humans feel bad when you take something away from them even if it increases their value position.
So, you want to stay above 0%. You want to be far from 10%. For a long time, the Fed said that we didn't know more than that, and refused to give a hard number. Recently, the Fed have given a "soft" number of 2% as the ideal, base on history and simulations. You could argue the details, but you will almost certainly come up with a number that is materially the same as 2% - remembering, of course, that this is not a directly controllable (or even perfectly measurable) number anyway.
That's why everyone fights about how much inflation really happened - it is basically impossible to measure, so you have to take any particular measurement and only apply it when the situation is "normal" for that measurement. (The classic example being including the price of oil in inflation, and then predicting starvation or the poor because of high inflation)