++++Maybe constant repetition, despite the snow on the ground, lulled those pilots into believing that with operative anti-skid, autospoilers and thrust reversers, the landing should have been no problem?+++
No doubt that over time, one accumulates a personal 'database' of events. In any endeavor, the 'been there, done that' attitude can develop due to repetition. Same airport, same approach, same winds, same.. same.. same.
A few years ago a SW Capt Steve Swauger wrote and presented a paper on how experienced pilots can respond like novices when presented with a situation well outside the routine. I can not find it on the net currently but it is an EXCELLENT discussion worth reading and for any pilot, thinking about its application. One major point was that IF you have to be constantly revising your solution to the problem, you probably are working with a failed solution and it is time to abandon the effort and begin again.
A second point is that we, as aviators, quickly respond to the blinking red light and the honking horn but we can miss the cues when things are failing but doing so only gradually. And when you add reinforcement from other sources such as no one missing the approach, no one going around, no one having problems clearing the runway after landing, no reports of braking problems, one would have to be somewhat psychic to conclude that the day is anything other than just another day at the office.