Forget inflation, and look at the load factors and route profits. Aim for maximum profits (usually that is a LF between 75-90%).
In other words charge the maximum possible prices that still gives you a decent LF, and do not aim for 100% LF as that means you are selling it too cheaply.
I agree with you Sami : but it can be time-consuming going into each route, then tweaking it up and down, checking the result of that, then re-tweaking again until you find that magic point of maximum profitability. Sometimes its easier to just set a 'fleet' standard of price v. LF that achieves a satisfactory, if not perfect, profit level, especially if you are a time-limited player.
Of course, if there was a way for a player to 'fix' their own 'default' price per route, allowing the 'reset' button to go to that, rather than the systems default price ; then it would allow for a much more efficient way to achieve overall price movements using the 'increase/decrease all price by x%' function.
oh dear, I feel a feature request coming on...