Desensitization to cautions and advisories. There are lot of conditions with landing criteria in which the plane will keep flying just fine. It may only be due to George working his magic under the glass, but the point is you can have a lot wrong with a V-22 and it not be shaking itself to pieces. It's only when it's REALLY bad that people begin to consider declaring.Why do you think that is the case?
One instance in my first squadron when a crew declared was while experiencing significant controllability issues after takeoff. There's something about the plane not going where you're telling it to go that scares people (rightfully so). The other was a nacelle fire that wouldn't go out even after blowing the bottle.