Why does anybody, if anybody, honestly listen to them?

Why do people honestly listen to critics. From what I've noticed and come to understand, critics are nothing but whiny little snobs who are totally biased towards one genre of movie, video game, television show, etc., to another, and they're still ped off as "intellectuals". Has it ever occurred to critics that their reviews have no influence on how much money a movie grosses? For example; Robbin Williams in World's Greatest Dad was hailed as a masterpiece by numerous critics, but it was a nightmarish failure at the box office. Transformers 2 on the other hand was slandered by critics but it made more than $8 hundred million worldwide. Instead of a bunch of snobs who think they know everything there is about making good media, why can't we just have people who yze media for certain themes or notable characteristics certain media has?