The training I recieved for glacier travel recommended clipping into a locker with a figure-8 on a bight or a butterfly.
A reason for this is if a roped climbing partner falls into a crevasse and cannot climb out under their own power, a pulley system (drop C or z-pulley) may be needed to assist with the extraction.
In order to set up one of the pulley systems, one would have to unclip from their clip in point so as to free up the section of the rope for the pulley system to work. This is after an anchor has been built.
Of course, the climber would also still be attached to the rope via a prusik, or clipped into the anchor itself.
Unclipping from a biner would be quick and easy while your climbing partner is in a crevasse, possibly injured, and most likely getting colder by the second.
With the glacier travel aside, I wouldn't tie or clip into a biner either while rock climbing.
So I don't disagree with you there.
Back on the original topic, inspection of all personal gear should be a standard procedure for climbers.
Info on gear, conditioning, and preparation for hiking/climbing.