I find it repugnant because I find it repugant.
You sound a bit like Self-PA here. You do realize that it is possible to misjudge your preferences due to factual mistakes? That's what the people in Eliezer's examples of scope insensitivity were doing. I don't see how you could determine the utility of one billion happy lives just by asking a human brain how it feels about the matter (ie without more complex introspection, preferably involving math).
Average utilitarianism leads to the conclusion that if someone of below average personal experiential utility, meaning the utility that they experience rather than the utility function that describes their preferences, can be removed from the world without affecting anyone else's personal experiential utility, then this should be done. My mind can understand one person's experiences, and I think that, as long as their personal experiential utility is positive*, doing so is wrong.
* Since personal experiential utility must be integrated over time, it must have a zero, unlike the utility functions that describe preferences.
I may misjudge my preferences, but unless someone else has convincing reasons to claim they know my preferences better than me, I'm sticking with them :-)
Btw, total utilitarianism has a problem with death as well. Most total utilitarians do not consider "kill this person, and replace them with a completely different person who is happier/has easier to satisfy preferences" as an improvement. But if it's not an improvement, then something is happening that is not captured by the standard total utility. And if total utilitarianism has to have an extra module that deals with death, I see no problem for other utility functions to have a similar module.
Some people see never-existed people as moral agents, and claim that we can talk about their preferences. Generally this means their personal preference in existing versus non-existing. Formulations such "it is better for someone to have existed than not" reflect this way of thinking.
But if the preferences of never-existed are relevant, then their non-personal perferences are also relevant. Do they perfer a blue world or a pink one? Would they want us to change our political systems? Would they want us to not bring into existence some never-existent people they don't like?
It seems that those who are advocating bringing never-existent people into being in order to satisfy those people's preferences should be focusing their attention on their non-personal preferences instead. After all, we can only bring into being so many trillions of trillions of trillions; but there is no theoretical limit to the number of never-existent people whose non-personal preferences we can satisfy. Just get some reasonable measure across the preferences of never-existent people, and see if there's anything that sticks out from the mass.