Finding out the prices of a large range of commodities is itself a costly enterprise, and knowledge of this fact by price setters is itself enough to… - Kenneth Arrow

This is by no means a "formal" matter. Clearly, the intuition behind the continuity requirement is a small step in the direction of utilitarian ethics; even the worst-off member of the society might be made to suffer if there is enough benefit to others. The assumption of diminishing marginal utility implies with regard to usual policy alternatives that there are better ways of improving the lot of better-off members than by hurting the worst-off.
But there is one striking case, of great practical importance, where our intuition is in favor of utilitarianism is some form as against any minimax rule. I refer to allocation over time. Typically, we expect future generations to be better off than we are. Should we save for them either directly or in the form of public investments? A maximin rule would surely say no. But if investment is productive, so that, in terms of goods, the next generation gains more than we lose, we usually feel that some investment is worthwhile even though the recipients will be better off than we are.

In fact, is is not a mere empirical accident that not all the contingent markets needed for efficiency exist but a necessary fact with deep implications for the workings and structure of economic institutions. Roughly speaking, information about particular events, even after they have occurred, is not spread evenly throughout the population. Two people cannot enter into a contract contingent on the occurrence of a certain event or state if only one of them in fact will know that the event has occurred. A particular example of this is sometimes known as “moral hazard” in the insurance and economic literature. The very existence of insurance will change individual behavior in the direction of less care in avoiding risks.

The problem I have with utilitarianism is not that it is excessively rational, but that the epistemological foundations are weak. My problem is: What are those objects we are adding up? I have no objection to adding them up if there's something to add. But the one thing I retain from utilitarianism is that, basically, judgements are based on consequences. Certainly that's the sort of thing we do in the theory of the single individual under uncertainty; you make sure utility is defined only over the consequences. I view rights as arrangements which may help you in achieving a higher utility level.