Utilitarianism is normative, so it means that your utility should be the average of the utility of all beings capable of experiencing it, regardless of whether your utility currently is that. If it becomes a weighted average, it ceases to be utilitarianism, because it involves considerations other than the maximization of utility.
one tiny change in the mind would have to suddenly shift us from fully caring about a mind to not caring about it at all, which doesn't seem to be what humans do
Consider how much people care about the living compared to the dead. I think that's a counterexample to your claim.
r/Fitness does a weekly "Moronic Monday", a judgment-free thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. I thought this seemed like a useful thing to have here - after all, the concepts discussed on LessWrong are probably at least a little harder to grasp than those of weightlifting. Plus, I have a few stupid questions of my own, so it doesn't seem unreasonable that other people might as well.