That's right, inflation has no effect on subsistence farmers and wage-slaves, who spend all their money pretty much as soon as they get it - assuming that pay rates keep step with the cost of living, which is not always the case.
But inflation has a very negative effect on people with savings and investments, because the real value of these is diluted over time. It strongly exaggerates the "time value of money" concept, and indeed amplifies it.
Historically, when Britain and other major countries used a precious-metal standard, mild and controlled deflation resulted, because population growth exceeded that of stocks of metals. Deflation is usually cited as a Bad Thing because capital owners can just let their money sit around instead of investing it, and it's value will go up anyway. But this ignores the fact that investment is always a sound rational choice if the expected return is higher than unity, regardless of inflation or deflation, and that most people now save using banks, which are in a position to invest those deposits wholesale.
Because people are irrational, people with significant amounts of capital are now tempted to speculate on the market by the possibility of greater-than-inflation returns. These people feel that they are losing out if they get anything less than the inflation rate, and would often be quite happy to leave it in a bank if deflation existed. But speculators are what cause bubbles, and bubbles always burst and crash.
There is one advantage of a fiat currency: governments can borrow money from the people, without asking, in a time of emergency (such as war), simply by having the Treasury print more money. It will be paid for automatically in the medium term, by inflation. But this only works, as we see from Greece's sorry example, if that government directly controls the issue of currency.
It is not possible to just "produce a load of extra gold". You'd better believe that gold mines are already working at or near capacity, and that gold is one of the most thoroughly recycled metals on the planet. That is why it is such a good store of value - even if an unusually large nugget were to be found unexpectedly, it would only have a small and temporary effect on the price. Silver also makes a good store of value (mind you, it is currently undervalued), though it takes up a lot more space for that purpose than gold does. Even copper has been used as an effective store of small amounts of value - if pennies were still made of solid copper, the metal would be inherently worth considerably more than face value - and still has a high enough scrap price that thieves often steal both live and abandoned electric cables.