Not well-loved, critics are important; they can draw public attention to work that might otherwise be overlooked. But their authority has been eroded by the democratization of criticism (spirit of the 60s, Amazon reviews, blogs etc) and by 'the idea that one opinion is as good as another'. This tendency is reinforced by the retreat of academic criticism into a highly specialized, technical language. Yet 'the death of the critic is to be mourned'.
That's my precis of an article by Rónán McDonald. The argument comes apart pretty quickly. The democratization of criticism, such as it is, is to be welcomed. It gives everyone a right, and the sense of having a right, to their own judgement in aesthetic matters - and why shouldn't they have this? It's not at all the same thing, however, as the idea that one opinion is as good as another or that everyone is an equally good judge. That doesn't apply in any sphere of activity, so why would it here? Which doesn't mean that the critic with greater knowledge of the relevant medium is always right against the wider public. In the way movies are received, it is sometimes the other way round.
Finally, if the activity of criticism is more widely diffused, then the critic isn't dead.