To condense what I see as your point: We don't want to change something and then quickly change it back, or it punishes people for changing.

But then again, the goal isn't to teach people to change - it's to teach people to make correct decisions. If something feels like punishment, that's a game design flaw - you want to make peoples' choices feel interesting, informed and impactful. The real culprit seems to be either withholding information about changes form the player (could be counteracted by giving notice ahead of time and being clearer about what sorts of things can happen), and making a system with lots of cost changes too complicated (counteracted by limiting the choices presented, breaking possible cost changes into sensible categories, introducing the player carefully).