The average of film critics shouldn't be in sync with the average of audiences, and that is okay! Critics watch movies from a different perspective of an audience member. Some really get pulled in by the technical details of the film while others are drawn to the story. Meanwhile the average movie goer's sole concern is entertainment. The best way to use movie critics is like a discovery service. Find several (4 or 5…
When critics diverge so far from the role of answering the question "what's a movie I would enjoy" then no, they're not doing their job. I'm not sure exactly what job they're doing now, but I'd say by and large they aren't doing anything I'm interested in.
That's like having a tourist blog that only talks about places that other tourist blogs like to blog about but not places people want to visit! Not useful for the (assumed) intended audience.