The point is that everybody have its own coefficients in such formulas.
Yes, everyone including the developers. And their coefficients will be the "correct" ones in the sense that the game is based around them. It may be impossible to compute how much population or culture one square is worth exactly, because it will vary to a certain degree depending on what building is used as a baseline. But, none the less, these values are neither arbitrary nor situational.
And while every player may need different things at different times that is hardly an argument for these things to be worthless. For example, when I first hit the woodelves, my evolving building were producing enough mana to get comfortably through the chapter. But that is no reason to argue that mana is "worthless" or that the burning fountain and the manta ray are bad buildings.
For any normal city culture is absolutly necessary. And by "normal" I mean any city that:
-is still progressing through research
-places guest race buildings
-is playing at least a few (magical) residences
-is playing factories
-does not have multiple fully leveled wonders yet
-is not plastered full with dozends of library sets, troop producing buildings or similar.
And if you don't think that those conditions constitute a "normal" city, we should probably petition the developers to start nerving again. Because then something has gone terribly wrong with the gamebalance.