When creating art, or pieces of culture, there are rules involved. There is a right way to go about making content and there is a wrong way. With writing, for example, there are grammar rules, pathos, the speed of a character's arc, tone, and description. These are all things which can be done right in any number of ways but they must be done correctly or else the story falls flat.
A critic is someone so versed in modern culture that they have seen and studied the multitudes of ways something can be done correctly. The deep critique they offer points out areas where the creator has done something incorrectly and has subsequently damaged the piece of culture they made. Without critics, creators would not receive the detailed and specific feedback they need in order to better their creations.
TLDR: Critic's feedback makes art and culture better. Stop hating. Read more classics and do things the right way. - Cheers