Summary: Evolution does not have moral consequences, and does not make cosmic purpose impossible.
number of critics see the use of selection theory in other than biological contexts as forcing malign political and moral commitments. A prime example of this is sociobiology, which is supposed to result in such things as eugenics, racism, and the death of the welfare state. Sociobiology, and the more recent evolutionary psychology movement, seeks to explain human behaviour in terms of the adaptations of human evolution. Gould especially has been vitriolic in his attacks on sociobiological explanations. It is thought by some to result in a completely selfish ethic known as rational egoism.
Another such view is "Social Darwinism", which holds that social policy should allow the weak and unfit to fail and die, and that this is not only good policy but morally right. The only real connection between Darwinism and Social Darwinism is the name. The real source of Social Darwinism is Herbert Spencer and the tradition going back to Hobbes via Malthus, not Darwin's own writings, though Darwin gained some inspiration on the effects of population growth from Malthus.
The claims made by Social Darwinists and their heirs suffer from the ethical fallacy known as "the naturalistic fallacy" (no connection to naturalism in explanations and the study of knowledge mentioned above). This is the inference from what may be the case to the conclusion that it is therefore right. However, while it is certainly true that, for example, some families are prone to suffer diabetes, as mine is, there is no licence to conclude that they should not be treated, any more than the fact that a child has a broken arm from a bicycle accident implies that the child should have a broken arm. David Hume long ago showed that "is" does not imply "ought".
In fact, diverse political and religious opinions characterise social musings based upon evolutionary biology. For example, the 19th century Russian anarchist aristocrat Pyotr Kropotkin wrote a book called Mutual Aid [1902, cf Gould 1992] in which he argued that evolution results more in cooperation than it does in harsh competition. His views are echoed in recent use of games theory to show that, in some cases at least, cooperation is a stable strategy for certain populations to adopt [Axelrod 1984].
Evolutionary theory doesn't exclude Purpose from Life, although it does remove the need for purposive design from a lot of the living realm (ie, all but the genetically engineered bit of the living realm). This apparent confusion is resolved if we ask of evolutionary theory two questions: one, is there a design evident in the structure of living organisms? Two, is there a universal purpose to life in general? Science answers No to the first question. Design is not directly evident in living things, although there is a marvellous complexity and adaptivity of life to its environment. To the second question, science of any kind answers: Insufficient Information. That kind of answer you get elsewhere - from a personal commitment or religious belief in some revelation.