In what conditions do airline pilots favor crabbing over de-crabbing for crosswind landings?
First, I would say that the question should be between Crab technique vs sideslip technique. What the wikipedia article describes as De-crab technique is simply a quick transition from crabbing to a momentary sideslip as the wheels touch down. Generally, landing while crabbed is bad form, regardless of type or size of aircraft due to the side load on the landing gear at touchdown.

I was taught that side slip technique (where you fly with the down wind wing slightly elevated and use rudder to keep fuselage and wheels lined up with the centerline) is preferred because you don't have to do any last second adjustments right before touchdown. If you do this correctly, the turning tendency of the aircraft is mostly cancelled out by the cross wind component. Also, if you do this right, you touch down with upwind mains first, then downwind mains.

However, I was also taught that side slip makes passengers feel uncomfortable, and that is why airliners stay in the "crab" until last second. 

As to your comment about airliners failing to de-crab, I've seen that too, I argue its just bad technique. Its difficult to properly execute the de-crab, it takes finesse and good timing.