There are plenty of examples of "critical" utopias which do not try to be absolutely perfect, and acknowledge where they fall down. Anarres in the Dispossessed by Le Guin, and the Culture novels by Iain M Banks might be two examples. They're still vastly preferable (imo) to current life on earth.

Huxley's _Island_ didn't seem too bad. I think the general problem is, if you want to completely eliminate crime, poverty, and conflict in general, you have to have a society that is extremely regimented, and you have to be willing to kill off anyone who seems "defective".