The things you mention are what inflation is meant to nullify. In an economists perfect world the amount of a normal good you can buy with $1 would be the same as the amount of that good you could buy for 1 inflation-adjusted dollar at any other time in history.
You're right, an inflation-adjusted dollar should buy some fixed fraction of e.g. a loaf of bread at any time in history. It's just such a multidimensional space that any one number is bound to leave out some pretty crucial information as to how much money a given person needs to be happy.
