We are not wired for overal utility/rational management of life
A rational men, calculates every move (& and smile) with his sum total of utility in mind. If you forget calculation costs, this is sensible. You have a total of love, money, health, rest, exerience etc. And every move and decisoin goes for the maximization of this sum total.
Problem is, nature has not wired us to act this way. We have specified emltional systems, drives etc.
Feeling hunger is the activation of a complex army of sensations motivations and thoghts that are solely geared towards eating. Same for sexual lust, wisdom search (assuming there is a natural tendency for searching wisdom.....) etc.
Besides that we are not wired for rational....
Acting and thinking in the rational summation way, kills (or weakens) the natural systems and dynamics. If when you are horney (and in bed with someone) you tell yourself "it is healthy to fuck", not only is this ludicrous, it literaly kills the natural system that says (cries) *sex*
That is why utilitarians are stupid
When you judge everything in terms of its overal utility, you lose appreciating the peculiarities, the specific, the beautiful and the experiental aspects of life.
Not only is it a lose of experience, but a lose of understanding. Life is in the specific, in the non summarized