The problem with those who want to value humans based on their utility is that there is no standard for utility unless humans (or something else) have (has) axiomatic value. If humans are basically worthless, then what difference does it make if something is useful to one of them? Sure, some people are drains on society and some contribute, but at the end of the day, why is society valuable?
Unless you accept some axiomatic value for humans or for something else that humans can serve, even as a starting point, you can't assign them any utilitarian value. The axiomatic value should, in my opinion, be equal, or at least I see that as the least arbitrary of the arbitrary systems of values you could assign to people.
Perhaps utility can create a second-order value; that is, a person's total value is his axiomatic value plus or minus his utility to other persons times these other people's axiomatic values. But there has to be a starting point that is either pre-logical (axiomatic, that is, it isn't deduced from other principles) or else circular.
That is all.