In a recent acticle written by Avise and published in PNAS (Avise 2010) the author gives some reaons why
evolution routinely yields suboptimal biological outcomes
From fauceir point of view it is the other way around. Imperfection is the prerequisit of evolution to take place. Even if you consider natural selection as the only driving force of evolution, you have to accept that without imperfection selection makes no sense.