Utopia is impossible I think. By nature animals tend to break off into communites, packs, groups, etc. Most other animals either stick to their own packs, or to themselves.
Humans differ from the other animals in the extremes we seek to stick in our "packs".
Where as most animals will just run out "undesireables", humans will often times seek to go further and inflict actual injury.
We as a species encompass such a broad range of levels between good and evil, this means that despite all the good one human can do, there is another that can do just as much bad.
No matter how many people who may be able to be "talked into sense" there will always be those who will seek to seclude, segragate, or out and out fight with others.
Hate is as intergal to human nature as love it seems, and this effects out interactions with our enviroment as well as with each other.