I perfectly agree that utility maximisation is indeed the proper way to resolve common moral conflicts.

But utility functions can be as complex as you need them to be! Saying you have a utility function does not constrain you virtually at all. But sometimes total utilitarians like to claim that their version is better because it is "simpler" or "more intuitive".

First of all, simplicity is not a virtue comparable with, say, human lives or happines, secondly I have different intuitions to them, and thirdly, their actual real utility function, if it were specified, would be unbelievably complex anyway.

I don't want to pour important moral insights down the drain, based on specious simplicity arguments....