I liked the link.
I would probably be uncomfortable with nudity and public sex too (at first), but it's not really a part of my personality that I like. If I had the chance, I would basically just try to get used to it. I don't want to make people who wouldn't want to adapt adapt, but I would rather that future people were not limited like me than that things stayed nice for people who had been raised in the bad old days like you and me.
I understand your reaction to the thought of killing Mother Nature. I would do it with some regret. I agree that she is beautiful, and I would miss her from an aesthetic point of view. But I think it's worth it.
The idea of wiping out other species to prevent their suffering strikes me as pretty bizarre. It's the same sort of extension of Negative Utilitarianism that leads to the suggestion that we should do the same to humanity, and I don't think that's a very practical approach to utility maximizing.
In any case, I doubt most of the natural world suffers nearly as much as the philosophers in that link suggest, partly because I suspect a lack of abstract awareness and other neurological faculties limits the ways in which most animals can suffer, and partly due to the same hedonic treadmill tendencies that exist in humans.
Assume for the time being that it will forever remain beyond the scope of science to change Human Nature. AGI is also impossible, as is Nanotech, BioImmortality, and those things.
Douglas Adams mice finished their human experiment, giving to you, personally, the job of redesigning earth, and specially human society, according to your wildest utopian dreams, but you can't change the unchangeables above.
You can play with architecture, engineering, gender ratio, clothing, money, science grants, governments, feeding rituals, family constitution, the constitution itself, education, etc... Just don't forget if you slide something too far away from what our evolved brains were designed to accept, things may slide back, or instability and catastrophe may ensue.
Finally, if you are not the kind of utilitarian that assigns exactly the same amount of importance to your desires, and to that of others, I want you to create this Utopia for yourself, and your values, not everyone.
The point of this exercise is: The vast majority of folk not related to this community that I know, when asked about an ideal world, will not change human nature, or animal suffering, or things like that, they'll think about changing whatever the newspaper editors have been writing about last few weeks. I am wondering if there is symmetry here, and folks from this community here do not spend that much time thinking about those kinds of change which don't rely on transformative technologies. It is just an intuition pump, a gedankenexperiment if you will. Force your brain to face this counterfactual reality, and make the best world you can given those constraints. Maybe, if sufficiently many post here, the results might clarify something about CEV, or the sociology of LessWrongers...