Inflation has existed ever since the invention of money. It is always decried as a bad thing which must be eliminated or at least controlled. Lately the absolutist position of earlier ages has been replaced by inflation "targeting" by central banks. The current head of the US Federal Reserve, Ben Bernanke, even wrote a book on the subject.
My understanding of why inflation is regarded as something to be prevented depends on a model of social and economic interests. In my model there are three broad classes of people. The lowest class, the working class and the rentier class.