But sometimes they are. I recall hearing of a commercial flight somewhere in South or Central America where the pitot was blocked and the pilots kept pitching up and cutting power trying to "slow" the aircraft down. They did that until they stalled the airplane and it made a hole in the ground.
This is precisely why you don't have one instrument in the cockpit and why you practice partial panel flight. One problem that is growing even in the general aviation community is that you have new and/or young pilots who believe everything their electronic displays tell them. Certainly a jet (particularly an Airbus) is much more sophisticated, but there seems to be a growing tendency among pilots of all stripes to believe that simply because you've got more electronic gizmos in the cockpit, you can fly into conditions you shouldn't be flying into. "The glass panel/gps/satellite weather/traffic avoidance/autopilot will get us there." Even if the pitot hadn't failed in this instance, I believe there was an excellent chance the aircraft couldn't have sustained the tremendous forces of that storm anyway.