If this is an essay, and you cant think of any dont make them up or ask others and then just write it around those reasons. Say no, we dont need/like them, and explain your answer well.
The teacher isnt trying to see if why we like gossip magazines, they want to see that u can argue. give 6 reasons why we DONT need them.
i'll start you off, they destroy the lives of many young girls with their airbrushed pictures and 'perfect' body shapes.